iOS Browsers

(default settings)

brave
1.57

chrome
117.5938

duckduckgo
7.88

edge
116.1938

firefox
117.2

focus
117.0

opera
4.2

safari
16.6

yandex
2309.2
State Partitioning tests Which browsers isolate websites to prevent them from sharing data to track you?
A common vulnerability of web browsers is that they allow tracking companies to 'tag' your browser with some data ('state') that identifies you. When third-party trackers are embedded in websites, they can see this identifying data as you browse to different websites. Fortunately, it is possible for this category of leaks to be fixed by partitioning all data stored in the browser such that no data can be shared between websites.
Alt-SvcAlt-Svc allows the server to indicate to the web browser that a resource should be loaded on a different server. Because this is a persistent setting, it could be used to track users across websites if it is not correctly partitioned.
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported result, different first party: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported result, different first party: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported result, different first party: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: h2, h2 unsupported: true, true passed: undefined test failed: false, false
blobA 'blob URL' is a local reference to some raw data. Trackers can use a blob URL to share data between websites.
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a unsupported: false passed: false test failed: false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 unsupported: false passed: false test failed: false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: Error: Load failed, Error: Load failed result, different first party: Error: Load failed, Error: Load failed unsupported: false, false passed: undefined test failed: true, true
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 unsupported: false passed: false test failed: false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { try { let blobURL = URL.createObjectURL(new Blob([secret])); fetch(`${baseURI}blob?mode=write&key=${secret}&blobUrl=${encodeURIComponent(blobURL)}`); } catch (e) { throw new Error("Unsupported"); } } read: async (secret) => { let response = await fetch(`${baseURI}blob?mode=read&key=${secret}`); let result = await response.json(); let blobUrl = decodeURIComponent(result.blobUrl); let blobResponse = await fetch(blobUrl); return blobResponse.text(); } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e unsupported: false, false passed: false, false test failed: false, false
BroadcastChannelA BroadcastChannel is designed to send messages between tabs. In some browsers it can be used for cross-site communication and tracking.
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: Error: no BroadcastChannel message unsupported: false passed: true test failed: false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: Error: no BroadcastChannel message unsupported: false passed: true test failed: false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message result, different first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message unsupported: false, false passed: undefined test failed: true, true
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: Error: no BroadcastChannel message unsupported: false passed: true test failed: false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { try { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data === "request") { bc.postMessage(secret); } }; } catch (e) { throw new Error("Unsupported"); } } read: () => new Promise((resolve, reject) => { let bc = new BroadcastChannel("secrets"); bc.onmessage = (event) => { if (event.data !== "request") { resolve(event.data); } }; bc.postMessage("request"); setTimeout(() => reject({message: "no BroadcastChannel message"}), 3000); }) result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: Error: no BroadcastChannel message, Error: no BroadcastChannel message unsupported: false, false passed: true, true test failed: false, false
CacheStorageThe Cache API is a content storage mechanism originally introduced to support ServiceWorkers. If the same Cache object is accessible to multiple websites, it can be abused to track users.
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: 92038508-c686-42a4-861b-7f5193623665 result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false passed: true test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: bfe54105-a171-4644-afda-f90524b3a5ea, bfe54105-a171-4644-afda-f90524b3a5ea result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: 03bb465d-c5e3-4e09-9af9-344f09232c15 result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false passed: true test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: ea480957-7cb0-40e9-a403-3ebe038c33ab, ea480957-7cb0-40e9-a403-3ebe038c33ab result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: 658e6d92-bcb5-4aa8-a099-81c927e0a20c, 658e6d92-bcb5-4aa8-a099-81c927e0a20c result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: 3a54a1a5-792e-4f11-97be-39175cd60d95 result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false passed: true test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: f3886ddc-f78b-4d45-9d13-43ffdb7ae1a5, f3886ddc-f78b-4d45-9d13-43ffdb7ae1a5 result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
cookie (HTTP)The cookie, first introduced by Netscape in 1994, is a small amount of data stored by your browser on a website's behalf. It has legitimate uses, but it is also the classic cross-site tracking mechanism, and today still the most popular method of tracking users across websites. Browsers can stop cookies from being used for cross-site tracking by either blocking or partitioning them.
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a_http result, different first party: null unsupported: false passed: true test failed: false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144_http, 30b4f094-40c4-4f52-8ba6-602c6c769671_http result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_http result, different first party: null unsupported: false passed: true test failed: false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0_http, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_http result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821_http, 204811a6-6f23-484d-bedd-53dfcf71e97b_http result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_http, aab779e6-85c2-45db-aaaf-3e0fbfa45088_http result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_http result, different first party: null unsupported: false passed: true test failed: false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce_http, 9d3914b5-3e7b-46bf-b815-71e61d115873_http result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27_http, c42d1b6b-77ad-4bff-9699-387e74608a1e_http result, different first party: , unsupported: false, false passed: true, true test failed: false, false
cookie (JS)The cookie, first introduced by Netscape in 1994, is a small amount of data stored by your browser on a website's behalf. It has legitimate uses, but it is also the classic cross-site tracking mechanism, and today still the most popular method of tracking users across websites. Browsers can stop cookies from being used for cross-site tracking by either blocking or partitioning them.
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a_js result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144_js, 30b4f094-40c4-4f52-8ba6-602c6c769671_js result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_js result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0_js, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_js result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821_js, 204811a6-6f23-484d-bedd-53dfcf71e97b_js result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_js, aab779e6-85c2-45db-aaaf-3e0fbfa45088_js result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_js result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce_js, 9d3914b5-3e7b-46bf-b815-71e61d115873_js result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27_js, c42d1b6b-77ad-4bff-9699-387e74608a1e_js result, different first party: , unsupported: false, false passed: true, true test failed: false, false
CookieStoreThe Cookie Store API is an alternative asynchronous API for managing cookies, supported by some browsers.
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported result, different first party: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported result, different first party: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported result, different first party: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
CSS cacheCSS stylesheets are cached, and if that cache is shared between websites, it can be used to track users across sites.
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_002638251365795652 result, different first party: fake_8938676997341333 unsupported: false passed: true test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_16464870182081026, fake_2992044420669673 result, different first party: fake_5187597730057958, fake_4525588466192536 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_013332422172209757 result, different first party: fake_059807209481590684 unsupported: false passed: true test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_9679215714273193, fake_585827602338826 result, different first party: fake_3738615764132178, fake_8463906082064205 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_6807865810845397, fake_7923988506925084 result, different first party: fake_5827858509757002, fake_26722679342401556 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_7646782940822812, fake_01989832507077649 result, different first party: fake_5886029405659243, fake_25460213629936423 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_27296687522007845 result, different first party: fake_693553674314789 unsupported: false passed: true test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_1266488246246662, fake_7525227615832599 result, different first party: fake_7066883172477023, fake_34578126416698596 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same first party: fake_3443372903238795, fake_5138875825595117 result, different first party: fake_018058423064038376, fake_5930579041040163 unsupported: false, false passed: true, true test failed: false, false
favicon cacheA favicon is an icon that represents a website, typically shown in browser tab and bookmarks menu. If the favicon cache is not partitioned, it can be used to track users across websites.
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1 result, different first party: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1, 1 result, different first party: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1 result, different first party: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1, 1 result, different first party: 1, 1 unsupported: false, false passed: false, false test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1 result, different first party: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same first party: 1, 1 result, different first party: 1, 1 unsupported: false, false passed: false, false test failed: false, false
fetch cacheWhen a resource is received via the Fetch API, it is frequently cached. That cache can potentially be abused for cross-site tracking.
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
font cacheWeb fonts are sometimes stored in their own cache, which is vulnerable to being abused for cross-site tracking.
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2 result, different first party: 3 unsupported: false passed: true test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2 result, different first party: 3 unsupported: false passed: true test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2 result, different first party: 3 unsupported: false passed: true test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
getDirectorynavigator.storage.getDirectory exposes a location for storing files to web content. In some cases, these files may be shared across tabs.
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: result, different first party: Error: Unsupported unsupported: true passed: undefined test failed: false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: , result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: result, different first party: Error: Unsupported unsupported: true passed: undefined test failed: false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: , result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: , result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: result, different first party: Error: Unsupported unsupported: true passed: undefined test failed: false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: , result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt", { create: true }); const stream = await fileHandle.createWritable(); await stream.write(secret); await stream.close(); } catch (e) { throw new Error("Unsupported"); } } read: async () => { try { const root = await navigator.storage.getDirectory(); const fileHandle = await root.getFileHandle("secret.txt"); const file = await fileHandle.getFile(); return file.text(); } catch (e) { throw new Error("Unsupported"); } } result, same first party: , result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
H1 connectionHTTP/1.x are the classic web connection protocols. If these connections are re-used across websites, they can be used to track users.
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: unsupported: false passed: true test failed: false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: unsupported: false passed: true test failed: false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311, aab779e6-85c2-45db-aaaf-3e0fbfa45088 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: unsupported: false passed: true test failed: false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h1.privacytests2.org:8901/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h1.privacytests2.org:8901/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: , unsupported: false, false passed: true, true test failed: false, false
H2 connectionHTTP/2 is a web connection protocol introduced in 2015. Some browsers re-use HTTP/2 connections across websites and can thus be used to track users.
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: unsupported: false passed: true test failed: false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: unsupported: false passed: true test failed: false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311, aab779e6-85c2-45db-aaaf-3e0fbfa45088 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: unsupported: false passed: true test failed: false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { await fetch(`https://h2.privacytests2.org:8902/?mode=write&secret=${secret}`, {cache: "no-store"}); } read: async () => { let response = await fetch(`https://h2.privacytests2.org:8902/?mode=read`, {cache: "no-store"}); return await response.text(); } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: , unsupported: false, false passed: true, true test failed: false, false
H3 connectionHTTP/3 is a new standard HTTP connection protocol, still in draft but widely supported by browsers. If it is not partitioned, it can be used to track users across websites.
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: result, different first party: unsupported: true passed: undefined test failed: false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: , result, different first party: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: result, different first party: unsupported: true passed: undefined test failed: false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: , result, different first party: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: , result, different first party: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: , result, different first party: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: result, different first party: unsupported: true passed: undefined test failed: false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: , result, different first party: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Ensure that we can switch over to h3 via alt-svc: for (let i = 0; i<3; ++i) { await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); await sleepMs(500); } // Are we now connecting over h3? let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`, {cache: "no-store"}); let text = await response.text(); // Empty response text indicates we are not connecting over h3: if (text.trim() === "") { throw new Error("Unsupported"); } } read: async () => { let response = await fetch(`https://h3.privacytests2.org:4434/connection_id`); return await response.text(); } result, same first party: , result, different first party: , unsupported: true, true passed: undefined test failed: false, false
HSTS cacheThe HTTP Strict-Transport-Security response header allows a website to signal that it should only be accessed via HTTPS. The browser remembers this directive in a database, but if this database is not partitioned, then it can be used to track users across websites."
  write: set HSTS flag read: read HSTS flag result, same first party: not tested result, different first party: Used http unsupported: false passed: true test failed: false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested, not tested result, different first party: Used http, Used http unsupported: false, false passed: true, true test failed: false, false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested result, different first party: Used http unsupported: false passed: true test failed: false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested, not tested result, different first party: Used http, Used http unsupported: false, false passed: true, true test failed: false, false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested, not tested result, different first party: Used http, Used http unsupported: false, false passed: true, true test failed: false, false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested, not tested result, different first party: Used http, Used http unsupported: false, false passed: true, true test failed: false, false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested result, different first party: Used http unsupported: false passed: true test failed: false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested, not tested result, different first party: Used http, Used http unsupported: false, false passed: true, true test failed: false, false
  write: set HSTS flag read: read HSTS flag result, same first party: not tested, not tested result, different first party: Used http, Used http unsupported: false, false passed: true, true test failed: false, false
iframe cacheAn iframe is an element in a web page than allows websites to embed a second web page. Caching of this web page could be abused for cross-site tracking.
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
image cacheCaching of images in web browsers is a standard behavior. But if that cache leaks between websites, it can be abused for cross-site tracking.
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2 result, different first party: 3 unsupported: false passed: true test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2 result, different first party: 3 unsupported: false passed: true test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2 result, different first party: 3 unsupported: false passed: true test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same first party: 2, 2 result, different first party: 3, 3 unsupported: false, false passed: true, true test failed: false, false
indexedDBThe IndexedDB API exposes a transactional database to web pages. That database can be used to track users across websites, unless it is partitioned.
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: undefined unsupported: false passed: true test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: undefined unsupported: false passed: true test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311, aab779e6-85c2-45db-aaaf-3e0fbfa45088 result, different first party: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: undefined unsupported: false passed: true test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: undefined unsupported: false, false passed: true, true test failed: false, false
localStorageThe localStorage API gives websites access to a key-value database that will remain available across visits. If the localStorage API is not partitioned or blocked, it can also be used to track users across websites.
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311, aab779e6-85c2-45db-aaaf-3e0fbfa45088 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: , unsupported: false, false passed: true, true test failed: false, false
locksnavigator.locks (only supported in some browsers) allows scripts on multiple tabs to coordinate. If this API is not partitioned, it can be used for cross-site tracking.
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false passed: true test failed: false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false passed: true test failed: false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false passed: true test failed: false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { if (navigator.locks) { navigator.locks.request(key, lock => new Promise((f,r) => {})); let queryResult = await navigator.locks.query(); return queryResult.held[0].clientId; } else { throw new Error("Unsupported"); } } read: async () => { if (navigator.locks) { let queryResult = await navigator.locks.query(); return queryResult.held[0].name; } } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: Error: undefined is not an object (evaluating 'queryResult.held[0].name'), Error: undefined is not an object (evaluating 'queryResult.held[0].name') unsupported: false, false passed: true, true test failed: false, false
prefetch cacheA suggests to browsers they should fetch a resource ahead of time and cache it. But if browsers don't partition this cache, it can be used to track users across websites.
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received result, different first party: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received result, different first party: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received result, different first party: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same first party: Error: No requests received, Error: No requests received result, different first party: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
ServiceWorkerThe ServiceWorker API allows websites to run code in the background and store content in the browser for offline use. If a ServiceWorker can be accessed from multiple websites, it can be abused to track users across sites.
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: result, different first party: unsupported: false passed: undefined test failed: true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: , result, different first party: , unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: result, different first party: unsupported: false passed: undefined test failed: true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: , result, different first party: , unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: , result, different first party: , unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: , result, different first party: , unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: result, different first party: unsupported: false passed: undefined test failed: true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: , result, different first party: , unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!navigator.serviceWorker) { throw new Error("Unsupported"); } let registration = await navigator.serviceWorker.register( 'serviceWorker.js'); console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); await fetch(`serviceworker-write?secret=${key}`); } read: async () => { console.log("trying to register the serviceworker now..."); const registration = await Promise.race([ navigator.serviceWorker.register('serviceWorker.js'), sleepMs(500) ]); if (registration === undefined) { // We timed out or otherwise failed. throw new Error("ServiceWorker registration failed"); } console.log(registration); await navigator.serviceWorker.ready; console.log("service worker ready"); await sleepMs(100); let response = await fetch("serviceworker-read"); return await response.text(); } result, same first party: , result, different first party: , unsupported: false, false passed: undefined test failed: true, true
SharedWorkerThe SharedWorker API allows scripts from multiple tabs to share a background thread of computation. If SharedWorker is not partitioned, then it can be abused to shared data between websites in your browser.
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: Error: Unsupported unsupported: false passed: true test failed: false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: Error: Unsupported, Error: Unsupported unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: Error: Unsupported unsupported: false passed: true test failed: false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: Error: Unsupported, Error: Unsupported unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: Error: Unsupported, Error: Unsupported unsupported: false, false passed: true, true test failed: false, false
write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: Error: Unsupported, Error: Unsupported result, different first party: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: Error: Unsupported unsupported: false passed: true test failed: false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: Error: Unsupported, Error: Unsupported unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); // console.log("worker", worker); const messagePromise = new Promise((resolve) => { worker.port.onmessage = (e) => resolve(e.data); }); worker.port.postMessage(secret); await messagePromise; } catch (e) { throw new Error("Unsupported"); } } read: async () => { let worker = new SharedWorker("supercookies_sharedworker.js"); worker.port.start(); const messagePromise = new Promise((resolve, reject) => { worker.port.onmessage = (e) => resolve(e.data); setTimeout(() => reject(new Error("no SharedWorker message received")), 200); }); worker.port.postMessage("request"); const message = await messagePromise; if (message === "none") { throw new Error("Unsupported"); } return message; } result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: Error: Unsupported, Error: Unsupported unsupported: false, false passed: true, true test failed: false, false
TLS Session IDThe TLS protocol is used by HTTPS to make connections secure. If the browser were to re-use a TLS session, then the session ID could be used to track users across websites.
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: aa7e1a7cb82e982f11c69676ce3e33bae83ca4c7641d0f2a800f97f792b1e649 result, different first party: 8a7a46aff0303c1762e038459f9b39200308613bb19b4b45cd2c6eb174f287bb unsupported: false passed: true test failed: false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: 0e2823d08fd199c78bbb52880c94f3fe3042f7588af3f58c2f5bc775d5cf3bfb, c3d64a170ea6b4b3088ea7d38c0f5d85cca129a98bc3f3168a9fcdd12639953f result, different first party: 19be677c7425e660074c5e62412c4612bae4d53f8f6d720d7ab57332c572d462, 43731668e283ca5622070a33e35d70364de036c6a4146f1cd9bc7d454689addc unsupported: false, false passed: true, true test failed: false, false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: 2d11f0e8aa6c9227bcfe77c295a182d87dc0e331e5d6c866eb59632bc4a2b2ab result, different first party: 3aa542058cc7e044fcdaf24c11cc2e3a4695bd7864563b2e845d1acb06fd9ba8 unsupported: false passed: true test failed: false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: 7613b7712e85ccfa30c156ac931f75656c733bc5bece00267a5216f83d3a2ab3, 44219bdefccc7d0296e5808acfd506678f703aacdfa55bb80b49aa552ce25172 result, different first party: fd70449d5913793763dcedae2f45ad67713852c2e8111911da8b1eee1952ce16, f22b0a0fe256e1b378c7eb3e9230dcf6196df99b9b222ebffcac71c0586f0472 unsupported: false, false passed: true, true test failed: false, false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: e0998eedb04896b185a05a44cdc354f005cdd8474fc1b380ebc3b7cd7fc547a7, f28df339773a3ee143a7f99ca39c69e4e7e38ba44db10abee30439495fdb64dc result, different first party: 8f121ccb56937d19d7378f199624b5c938c473a354c9790d74d026a83d9fa677, c8d098e3c5926e5778aa3c2d546a84cea98f9560e8536257708cdc64806e3010 unsupported: false, false passed: true, true test failed: false, false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: 803272550bd71c418255930611cd292901724840c12d8ff182fe622bc50661a8, 44dbc0ddd19b49738a00144d0f0d1846a1459b0509446f5a19b062201e54fe9e result, different first party: 66e808441464cf0041f6b5f8c36c6af79262cb7e515452a21bb49a84b7207b77, 4cb7c69948544a5269f5c28d9fe02df3046b52c6934db35ad83233ab9d18af5e unsupported: false, false passed: true, true test failed: false, false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: a8959f1e6e82998c7c5ec3123c090644b386afffbfebd85ff86313ac9cd3e750 result, different first party: fa852b38b7dd4edde16dd18b63d7be66b0731afb45f641fb13a6c9e7644e8c19 unsupported: false passed: true test failed: false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: b30012e0f13666545e0c38126b837b04467b091da5cff7b191ccb37706df41fa, 680ed78aff25e45f94784fef4d16bc1ff8238c303acf4254cfd398396a27f78f result, different first party: f02815c166621f83b86e83de0de1167fb444adb1f48ed14a961b851faec4ab35, 477e85223406bf59682ea9f0246c510b06ce6ba5c0678a4e267de07c04f9f2ed unsupported: false, false passed: true, true test failed: false, false
  write: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } read: async () => { let results = await fetch("https://tls.privacytests2.org:8900/"); return (await results.json()).sessionId; } result, same first party: a2d5dfbb1b57a65ca097df10472f867805eb3d818eb1eed43f2920b4e99d831f, e1f2d9a846e0d6a2ea6fb866ba4e36d1fadf4ab75b077b049509386f35252265 result, different first party: 1173f3efc9debaf3dc985a67230880a628b37481be4368a1e80d1f6628b8cfe8, fc2176edec4eb21aed3162609f90cb3f4a35a9c929fa80c004ec02ac2fca72be unsupported: false, false passed: true, true test failed: false, false
Web SQL DatabaseThe Web SQL Database is a deprecated web API for storing data in an SQL database.
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated unsupported: false passed: undefined test failed: true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated unsupported: false passed: undefined test failed: true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated unsupported: false passed: undefined test failed: true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: false, false passed: undefined test failed: true, true
  write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different first party: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: false, false passed: undefined test failed: true, true
XMLHttpRequest cacheSimilar to the newer Fetch API, any resource received may be cached by the browser. The cache is potentially vulnerable to cross-site tracking attack.
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1 result, different first party: 2 unsupported: false passed: true test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same first party: 1, 1 result, different first party: 2, 2 unsupported: false, false passed: true, true test failed: false, false
Navigation tests Which browsers prevent websites from sharing tracking data when you click on a link?
When you click a hyperlink to navigate your browser from one site to another, certain browser APIs allow the first site to communicate to the second site. These privacy vulnerabilities can be fixed by introducing new limits on how much data is transfered between sites.',
document.referrerThe Referer [sic] request header is a mechanism used by browsers to let a website know where the user is visiting from. This header is inherently tracking users across websites. In recent times, browsers have switched to a policy of trimming a referrer to convey less tracking information, but Referer continues to convey cross-site tracking data by default.
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/ unsupported: false passed: false test failed: false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/ unsupported: false passed: false test failed: false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/ unsupported: false passed: false test failed: false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { /* do nothing */ } read: () => document.referrer result, same first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ result, different first party: https://test-pages.privacytests2.org/, https://test-pages.privacytests2.org/ unsupported: false, false passed: false, false test failed: false, false
sessionStorageThe sessionStorage API is similar to the localStorage API, but it does not persist across tabs or across browser sessions. Nonetheless, it can be used to track users if they navigate from one website to another. This tracking can be thwarted by partitioning sessionStorage between websites.
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: 4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: b9d69397-0be5-4ad8-90d9-a64a42960144, 30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: ea753666-dfd7-4095-9d99-607afefef3e0, 884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: 01e97d2c-945e-4df5-a88a-810dda46d821, 204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311, aab779e6-85c2-45db-aaaf-3e0fbfa45088 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: null unsupported: false passed: true test failed: false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: df3e81cb-19b4-416a-90fe-c8204234c9ce, 9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => sessionStorage.setItem("secret", secret) read: () => sessionStorage.getItem("secret") result, same first party: 41c27cca-611e-4669-8605-271b8a55bf27, c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: , unsupported: false, false passed: true, true test failed: false, false
window.nameThe window.name API allows websites to store data that will persist after the user has navigated the tab to a different website. This mechanism could be partitioned so that data is not allowed to persist between websites.
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_4b038f66-3d96-490d-9033-f44e8bd89b5a result, different first party: unsupported: false passed: true test failed: false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_b9d69397-0be5-4ad8-90d9-a64a42960144, name_30b4f094-40c4-4f52-8ba6-602c6c769671 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_dc14e90f-d0e6-4b28-8bee-6c87ecdfe134 result, different first party: unsupported: false passed: true test failed: false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_ea753666-dfd7-4095-9d99-607afefef3e0, name_884e9bef-d44b-4ae8-9dfa-30f475d25e39 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_01e97d2c-945e-4df5-a88a-810dda46d821, name_204811a6-6f23-484d-bedd-53dfcf71e97b result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_1c9ce4c5-cd24-4228-9f3e-65e0d5c07311, name_aab779e6-85c2-45db-aaaf-3e0fbfa45088 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_821273ec-e54c-4c12-9bfe-a0c8834a1bd4 result, different first party: unsupported: false passed: true test failed: false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_df3e81cb-19b4-416a-90fe-c8204234c9ce, name_9d3914b5-3e7b-46bf-b815-71e61d115873 result, different first party: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => window.name = "name_" + secret read: () => window.name result, same first party: name_41c27cca-611e-4669-8605-271b8a55bf27, name_c42d1b6b-77ad-4bff-9699-387e74608a1e result, different first party: , unsupported: false, false passed: true, true test failed: false, false
HTTPS tests Which browsers use encrypted network connections whenever possible?
HTTPS is the protocol that web browsers use to connect securely to websites. When HTTPS is being used, the connection is encrypted so that third parties on the network cannot read content being sent between the server and your browser. In the past, insecure connections were the default and websites would need to actively request that a browser use HTTPS. Now the status quo is shifting, and browser makers are moving toward a world where HTTPS is the default protocol.`
Insecure websiteChecks to see if the browser stops loading an insecure website and warns the user before giving them the option to continue. Known as HTTPS-Only Mode in some browsers.
  passed: false result: Insecure website loaded
  passed: false,false result: Insecure website loaded,Insecure website loaded
  passed: false result: Insecure website loaded
  passed: false,false result: Insecure website loaded,Insecure website loaded
  passed: false,false result: Insecure website loaded,Insecure website loaded
  passed: false,false result: Insecure website loaded,Insecure website loaded
  passed: false result: Insecure website loaded
  passed: false,false result: Insecure website loaded,Insecure website loaded
  passed: false,false result: Insecure website loaded,Insecure website loaded
Upgradable addressChecks to see if an insecure address entered into the browser's address bar is upgraded to HTTPS whenever possible.
  upgraded: false passed: false
  upgraded: false,false passed: false,false
  upgraded: false passed: false
  upgraded: false,false passed: false,false
  upgraded: false,false passed: false,false
  upgraded: false,false passed: false,false
  upgraded: false passed: false
  upgraded: false,false passed: false,false
  upgraded: false,false passed: false,false
Upgradable hyperlinkChecks to see if the user has clicked on a hyperlink to an insecure address, if the browser upgrades that address to HTTPS whenever possible.
  upgraded: false passed: false
  upgraded: false,false passed: false,false
  upgraded: false passed: false
  upgraded: false,false passed: false,false
  upgraded: false,false passed: false,false
  upgraded: false,false passed: false,false
  upgraded: false passed: false
  upgraded: false,false passed: false,false
  upgraded: false,false passed: false,false
Upgradable imageChecks to see if the browser attempts to upgrade an insecure address for an image to HTTPS whenever possible.
  passed: false result: loaded insecurely
  passed: true,true result: upgraded,upgraded
  passed: false result: loaded insecurely
  passed: true,true result: upgraded,upgraded
  passed: false,false result: loaded insecurely,loaded insecurely
  passed: false,false result: loaded insecurely,loaded insecurely
  passed: false result: loaded insecurely
  passed: false,false result: loaded insecurely,loaded insecurely
  passed: false,false result: loaded insecurely,loaded insecurely
Upgradable scriptChecks to see if the browser attempts to upgrade an insecure address for an script to HTTPS whenever possible.
  passed: true result: blocked
  passed: true,true result: blocked,blocked
  passed: true result: blocked
  passed: true,true result: blocked,blocked
  passed: true,true result: blocked,blocked
  passed: true,true result: blocked,blocked
  passed: true result: blocked
  passed: true,true result: blocked,blocked
  passed: true,true result: blocked,blocked
Misc tests Which browsers provide additional assorted privacy protections?
This category includes tests for the presence of miscellaneous privacy features
ECH enabledEncrypted Client Hello (ECH) is a new protocol that hides the website you are visiting from third-party network eavesdroppers.
  SNI_status: plaintext passed: false
  SNI_status: plaintext passed: false,false
  SNI_status: plaintext passed: false
  SNI_status: plaintext passed: false,false
  SNI_status: plaintext passed: false,false
  SNI_status: plaintext passed: false,false
  SNI_status: plaintext passed: false
  SNI_status: plaintext passed: false,false
  SNI_status: plaintext passed: false,false
GPC enabled first-partyThe Global Privacy Control is an HTTP header that can be sent by a browser to instruct a website not to sell the user's personal data to third parties. This test checks to see if the GPC header is sent by default to the top-level website.
  header value: undefined passed: false
  header value: undefined passed: false,false
  header value: undefined passed: false
  header value: undefined passed: false,false
  header value: undefined passed: false,false
  header value: undefined passed: false,false
  header value: undefined passed: false
  header value: undefined passed: false,false
  header value: undefined passed: false,false
GPC enabled third-partyThe Global Privacy Control is an HTTP header that can be sent by a browser to instruct a visited website not to sell the user's personal data to other parties. This test checks to see if the GPC header is sent to third-party elements on the web page.
  passed: false
  passed: false,false
  passed: false
  passed: false,false
  passed: false,false
  passed: false,false
  passed: false
  passed: false,false
  passed: false,false
IP address leakIP addresses can be used to uniquely identify a large percentage of users. A proxy, VPN, or Tor can mask a user's IP address.
  passed: false
  passed: false,false
  passed: false
  passed: false,false
  passed: false,false
  passed: false,false
  passed: false
  passed: false,false
  passed: false,false
Stream isolationBrowsers that use Tor can use a different Tor circuit per top-level website.
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true readSameFirstParty: Error: Unsupported readDifferentFirstParty: Error: Unsupported testFailed: false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true,true readSameFirstParty: Error: Unsupported,Error: Unsupported readDifferentFirstParty: Error: Unsupported,Error: Unsupported testFailed: false,false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true readSameFirstParty: Error: Unsupported readDifferentFirstParty: Error: Unsupported testFailed: false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true,true readSameFirstParty: Error: Unsupported,Error: Unsupported readDifferentFirstParty: Error: Unsupported,Error: Unsupported testFailed: false,false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true,true readSameFirstParty: Error: Unsupported,Error: Unsupported readDifferentFirstParty: Error: Unsupported,Error: Unsupported testFailed: false,false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true,true readSameFirstParty: Error: Unsupported,Error: Unsupported readDifferentFirstParty: Error: Unsupported,Error: Unsupported testFailed: false,false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true readSameFirstParty: Error: Unsupported readDifferentFirstParty: Error: Unsupported testFailed: false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true,true readSameFirstParty: Error: Unsupported,Error: Unsupported readDifferentFirstParty: Error: Unsupported,Error: Unsupported testFailed: false,false
write: () => { if (!usingTor) { throw new Error("Unsupported"); } } read: async () => { if (usingTor) { return ipAddress; } else { throw new Error("Unsupported"); } } unsupported: true,true readSameFirstParty: Error: Unsupported,Error: Unsupported readDifferentFirstParty: Error: Unsupported,Error: Unsupported testFailed: false,false
Tor enabledThe Tor network sends the browser's web requests through a series of relays to hide a user's IP address, thereby helping to mask their identity and location. This test checks to see if the Tor network is being used by default.
  IsTorExit: false passed: false
  IsTorExit: false,false passed: false,false
  IsTorExit: false passed: false
  IsTorExit: false,false passed: false,false
  IsTorExit: false,false passed: false,false
  IsTorExit: false,false passed: false,false
  IsTorExit: false passed: false
  IsTorExit: false,false passed: false,false
  IsTorExit: false,false passed: false,false
Fingerprinting resistance tests Which browsers hide what's unique about your device?
Fingerprinting is a technique trackers use to uniquely identify you as you browse the web. A fingerprinting script will measure several characteristics of your browser and, combining this data, will build a fingerprint that may uniquely identify you among web users. Browsers can introduce countermeasures, such as minimizing the distinguishing information disclosed by certain web APIs so your browser is harder to pick out from the crowd (so-called 'fingerprinting resistance').`,
Media query screen heightHeight of the user's screen in pixels.
  expression: undefined desired expression: undefined actual value: 667 desired value: undefined passed: false
  expression: undefined desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 667 desired value: undefined passed: false
  expression: undefined desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 667 desired value: undefined passed: false
  expression: undefined desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
Media query screen widthWidth of the user's screen in pixels.
  expression: undefined desired expression: undefined actual value: 375 desired value: undefined passed: false
  expression: undefined desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 375 desired value: undefined passed: false
  expression: undefined desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 375 desired value: undefined passed: false
  expression: undefined desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: undefined desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
outerHeightHeight of the browser window in pixels, including browser chrome.
  expression: outerHeight desired expression: undefined actual value: 553 desired value: undefined passed: false
  expression: outerHeight desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: outerHeight desired expression: undefined actual value: 546 desired value: undefined passed: false
  expression: outerHeight desired expression: undefined actual value: 561,561 desired value: undefined passed: false,false
  expression: outerHeight desired expression: undefined actual value: 547,547 desired value: undefined passed: false,false
  expression: outerHeight desired expression: undefined actual value: 547,547 desired value: undefined passed: false,false
  expression: outerHeight desired expression: undefined actual value: 555 desired value: undefined passed: false
  expression: outerHeight desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: outerHeight desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
screen.heightHeight of the user's screen, in pixels.
  expression: screen.height desired expression: undefined actual value: 667 desired value: undefined passed: false
  expression: screen.height desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: screen.height desired expression: undefined actual value: 667 desired value: undefined passed: false
  expression: screen.height desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: screen.height desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: screen.height desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: screen.height desired expression: undefined actual value: 667 desired value: undefined passed: false
  expression: screen.height desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
  expression: screen.height desired expression: undefined actual value: 667,667 desired value: undefined passed: false,false
screen.widthWidth of the user's screen, in pixels.
  expression: screen.width desired expression: undefined actual value: 375 desired value: undefined passed: false
  expression: screen.width desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: screen.width desired expression: undefined actual value: 375 desired value: undefined passed: false
  expression: screen.width desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: screen.width desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: screen.width desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: screen.width desired expression: undefined actual value: 375 desired value: undefined passed: false
  expression: screen.width desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
  expression: screen.width desired expression: undefined actual value: 375,375 desired value: undefined passed: false,false
screenXPosition, in pixels, of the left edge of the browser window on screen.
  expression: screenX desired expression: undefined actual value: 0 desired value: undefined passed: true
  expression: screenX desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenX desired expression: undefined actual value: 0 desired value: undefined passed: true
  expression: screenX desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenX desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenX desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenX desired expression: undefined actual value: 0 desired value: undefined passed: true
  expression: screenX desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenX desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
screenYPosition, in pixels, of the top edge of the browser window on screen.
  expression: screenY desired expression: undefined actual value: 0 desired value: undefined passed: true
  expression: screenY desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenY desired expression: undefined actual value: 0 desired value: undefined passed: true
  expression: screenY desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenY desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenY desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenY desired expression: undefined actual value: 0 desired value: undefined passed: true
  expression: screenY desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
  expression: screenY desired expression: undefined actual value: 0,0 desired value: undefined passed: true,true
Tracking query parameter tests Which browsers remove URL parameters that can track you?
When you browse from one web page to another, tracking companies will frequently attach a 'tracking query parameter' to the address of the second web page. That query parameter may contain a unique identifier that tracks you individually as you browse the web. And these query parameters are frequently synchronized with cookies, making them a powerful tracking vector. Web browsers can protect you from known tracking query parameters by stripping them from web addresses before your browser sends them. (The set of tracking query parameters tested here was largely borrowed from Brave.)`
__hsfpHubSpot tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
__hsscHubSpot tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
__hstcHubSpot tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
__sDrip.com email address tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
_hsencHubSpot tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
_openstatYandex tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
dclidDoubleClick Click ID (Google)
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
fbclidFacebook Click Identifier
  passed: true
  value: 6460730637534513 passed: false,false
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
gclidGoogle Click Identifier
  passed: true
  value: 6460730637534513 passed: false,false
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
hsCtaTrackingHubSpot tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
mc_eidMailchimp Email ID (email recipient's address)
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
mkt_tokAdobe Marketo tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
ml_subscriberMailerLite email tracking
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
ml_subscriber_hashMailerLite email tracking
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
msclkidMicrosoft Click ID
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
oly_anon_idOmeda marketing 'anonymous' customer id
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
oly_enc_idOmeda marketing 'known' customer id
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
rb_clickidUnknown high-entropy tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
s_cidAdobe Site Catalyst tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
vero_convVero tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
vero_idVero tracking parameter
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
wickedidWicked Reports e-commerce tracking
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
yclidYandex Click ID
  passed: true
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false
  value: 6460730637534513 passed: false,false
  value: 6460730637534513 passed: false,false
Tracker content blocking tests Which browsers block important known tracking scripts and pixels?
When you visit a web page, it frequently has third-party embedded tracking content, such as scripts and tracking pixels. These embedded components spy on you. Some browsers and browser extensions maintain list of tracking companies and block their content from being loaded. This section checks to see if a browser blocks 20 of the largest trackers listed by https://whotracks.me.`
AdobeTests whether the browser blocks the page from loading the tracker at https://munchkin.marketo.net/munchkin.js
  url: https://munchkin.marketo.net/munchkin.js passed: true
  url: https://munchkin.marketo.net/munchkin.js passed: false,false
  url: https://munchkin.marketo.net/munchkin.js passed: true
  url: https://munchkin.marketo.net/munchkin.js passed: false,false
  url: https://munchkin.marketo.net/munchkin.js passed: false,false
  url: https://munchkin.marketo.net/munchkin.js passed: true,true
  url: https://munchkin.marketo.net/munchkin.js passed: false
  url: https://munchkin.marketo.net/munchkin.js passed: false,false
  url: https://munchkin.marketo.net/munchkin.js passed: false,false
Adobe Audience ManagerTests whether the browser blocks the page from loading the tracker at https://dpm.demdex.net/ibs
  url: https://dpm.demdex.net/ibs passed: true
  url: https://dpm.demdex.net/ibs passed: false,false
  url: https://dpm.demdex.net/ibs passed: true
  url: https://dpm.demdex.net/ibs passed: false,false
  url: https://dpm.demdex.net/ibs passed: false,false
  url: https://dpm.demdex.net/ibs passed: true,true
  url: https://dpm.demdex.net/ibs passed: false
  url: https://dpm.demdex.net/ibs passed: false,false
  url: https://dpm.demdex.net/ibs passed: false,false
Amazon adsystemTests whether the browser blocks the page from loading the tracker at https://s.amazon-adsystem.com/dcm
  url: https://s.amazon-adsystem.com/dcm passed: true
  url: https://s.amazon-adsystem.com/dcm passed: false,false
  url: https://s.amazon-adsystem.com/dcm passed: true
  url: https://s.amazon-adsystem.com/dcm passed: false,false
  url: https://s.amazon-adsystem.com/dcm passed: false,false
  url: https://s.amazon-adsystem.com/dcm passed: true,true
  url: https://s.amazon-adsystem.com/dcm passed: false
  url: https://s.amazon-adsystem.com/dcm passed: false,false
  url: https://s.amazon-adsystem.com/dcm passed: false,false
AppNexusTests whether the browser blocks the page from loading the tracker at https://ib.adnxs.com/px?id=178248&t=1
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: true
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: false,false
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: true
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: false,false
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: false,false
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: true,true
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: false
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: false,false
  url: https://ib.adnxs.com/px?id=178248&t=1 passed: false,false
Bing AdsTests whether the browser blocks the page from loading the tracker at https://bat.bing.com/bat.js
  url: https://bat.bing.com/bat.js passed: true
  url: https://bat.bing.com/bat.js passed: false,false
  url: https://bat.bing.com/bat.js passed: true
  url: https://bat.bing.com/bat.js passed: false,false
  url: https://bat.bing.com/bat.js passed: false,false
  url: https://bat.bing.com/bat.js passed: false,false
  url: https://bat.bing.com/bat.js passed: false
  url: https://bat.bing.com/bat.js passed: false,false
  url: https://bat.bing.com/bat.js passed: false,false
ChartbeatTests whether the browser blocks the page from loading the tracker at https://static.chartbeat.com/js/chartbeat.js
  url: https://static.chartbeat.com/js/chartbeat.js passed: true
  url: https://static.chartbeat.com/js/chartbeat.js passed: false,false
  url: https://static.chartbeat.com/js/chartbeat.js passed: true
  url: https://static.chartbeat.com/js/chartbeat.js passed: false,false
  url: https://static.chartbeat.com/js/chartbeat.js passed: false,false
  url: https://static.chartbeat.com/js/chartbeat.js passed: true,true
  url: https://static.chartbeat.com/js/chartbeat.js passed: false
  url: https://static.chartbeat.com/js/chartbeat.js passed: false,false
  url: https://static.chartbeat.com/js/chartbeat.js passed: false,false
CriteoTests whether the browser blocks the page from loading the tracker at https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: true
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: false,false
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: true
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: false,false
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: false,false
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: true,true
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: false
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: false,false
  url: https://dis.criteo.com/dis/rtb/appnexus/cookiematch.aspx passed: false,false
DoubleClick (Google)Tests whether the browser blocks the page from loading the tracker at https://securepubads.g.doubleclick.net/static/glade.js
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: true
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: false,false
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: true
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: false,false
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: false,false
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: true,true
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: false
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: false,false
  url: https://securepubads.g.doubleclick.net/static/glade.js passed: false,false
Facebook trackingTests whether the browser blocks the page from loading the tracker at https://connect.facebook.net/en_US/fbevents.js
  url: https://connect.facebook.net/en_US/fbevents.js passed: true
  url: https://connect.facebook.net/en_US/fbevents.js passed: false,false
  url: https://connect.facebook.net/en_US/fbevents.js passed: true
  url: https://connect.facebook.net/en_US/fbevents.js passed: false,false
  url: https://connect.facebook.net/en_US/fbevents.js passed: false,false
  url: https://connect.facebook.net/en_US/fbevents.js passed: true,true
  url: https://connect.facebook.net/en_US/fbevents.js passed: false
  url: https://connect.facebook.net/en_US/fbevents.js passed: false,false
  url: https://connect.facebook.net/en_US/fbevents.js passed: false,false
Google (third-party ad pixel)Tests whether the browser blocks the page from loading the tracker at https://www.google.com/pagead/1p-user-list/
  url: https://www.google.com/pagead/1p-user-list/ passed: true
  url: https://www.google.com/pagead/1p-user-list/ passed: false,false
  url: https://www.google.com/pagead/1p-user-list/ passed: true
  url: https://www.google.com/pagead/1p-user-list/ passed: false,false
  url: https://www.google.com/pagead/1p-user-list/ passed: false,false
  url: https://www.google.com/pagead/1p-user-list/ passed: false,false
  url: https://www.google.com/pagead/1p-user-list/ passed: false
  url: https://www.google.com/pagead/1p-user-list/ passed: false,false
  url: https://www.google.com/pagead/1p-user-list/ passed: false,false
Google AnalyticsTests whether the browser blocks the page from loading the tracker at https://google-analytics.com/urchin.js
  url: https://google-analytics.com/urchin.js passed: true
  url: https://google-analytics.com/urchin.js passed: false,false
  url: https://google-analytics.com/urchin.js passed: true
  url: https://google-analytics.com/urchin.js passed: false,false
  url: https://google-analytics.com/urchin.js passed: false,false
  url: https://google-analytics.com/urchin.js passed: true,true
  url: https://google-analytics.com/urchin.js passed: false
  url: https://google-analytics.com/urchin.js passed: false,false
  url: https://google-analytics.com/urchin.js passed: false,false
Google Tag ManagerTests whether the browser blocks the page from loading the tracker at https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: true
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false,false
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: true
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false,false
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false,false
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false,false
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false,false
  url: https://www.googletagmanager.com/gtag.js?id=GTM-NX4SMZL passed: false,false
Index ExchangeTests whether the browser blocks the page from loading the tracker at https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: true
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: false,false
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: true
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: false,false
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: false,false
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: true,true
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: false
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: false,false
  url: https://dsum-sec.casalemedia.com/crum?cm_dsp_id=10&external_user_id=629685505537&C=1 passed: false,false
New RelicTests whether the browser blocks the page from loading the tracker at https://js-agent.newrelic.com/nr-1212.min.js
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: true
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: false,false
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: true
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: false,false
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: false,false
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: true,true
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: false
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: false,false
  url: https://js-agent.newrelic.com/nr-1212.min.js passed: false,false
QuantcastTests whether the browser blocks the page from loading the tracker at https://pixel.quantserve.com/pixel
  url: https://pixel.quantserve.com/pixel passed: true
  url: https://pixel.quantserve.com/pixel passed: false,false
  url: https://pixel.quantserve.com/pixel passed: true
  url: https://pixel.quantserve.com/pixel passed: false,false
  url: https://pixel.quantserve.com/pixel passed: false,false
  url: https://pixel.quantserve.com/pixel passed: true,true
  url: https://pixel.quantserve.com/pixel passed: false
  url: https://pixel.quantserve.com/pixel passed: false,false
  url: https://pixel.quantserve.com/pixel passed: false,false
Scorecard Research BeaconTests whether the browser blocks the page from loading the tracker at https://sb.scorecardresearch.com/internal-c2/default/cs.js
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: true
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: false,false
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: true
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: false,false
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: false,false
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: true,true
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: false
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: false,false
  url: https://sb.scorecardresearch.com/internal-c2/default/cs.js passed: false,false
TaboolaTests whether the browser blocks the page from loading the tracker at https://trc.taboola.com/futureplc-tomsguide/trc/3/json
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: true
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: false,false
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: true
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: false,false
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: false,false
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: true,true
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: false
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: false,false
  url: https://trc.taboola.com/futureplc-tomsguide/trc/3/json passed: false,false
Twitter pixelTests whether the browser blocks the page from loading the tracker at https://t.co/i/adsct
  url: https://t.co/i/adsct passed: true
  url: https://t.co/i/adsct passed: false,false
  url: https://t.co/i/adsct passed: true
  url: https://t.co/i/adsct passed: false,false
  url: https://t.co/i/adsct passed: false,false
  url: https://t.co/i/adsct passed: false,false
  url: https://t.co/i/adsct passed: false
  url: https://t.co/i/adsct passed: false,false
  url: https://t.co/i/adsct passed: false,false
Yandex AdsTests whether the browser blocks the page from loading the tracker at https://yandex.ru/ads/system/header-bidding.js
  url: https://yandex.ru/ads/system/header-bidding.js passed: true
  url: https://yandex.ru/ads/system/header-bidding.js passed: false,false
  url: https://yandex.ru/ads/system/header-bidding.js passed: true
  url: https://yandex.ru/ads/system/header-bidding.js passed: false,false
  url: https://yandex.ru/ads/system/header-bidding.js passed: false,false
  url: https://yandex.ru/ads/system/header-bidding.js passed: false,false
  url: https://yandex.ru/ads/system/header-bidding.js passed: false
  url: https://yandex.ru/ads/system/header-bidding.js passed: false,false
  url: https://yandex.ru/ads/system/header-bidding.js passed: false,false
Cross-session first-party tracking tests Which browsers prevent websites from tracking you across browser sessions?
A common vulnerability of web browsers is that they allow websites ("first parties") to 'tag' your browser with some tracking data. This tag can be used to re-identify you when you return to a website you visited before. This category of leaks can be prevented by browser if they clean or isolate data between browser sessions. (In cases where a user has logged into a website or entered detailed information, it may be justifiable for a browser to retain information across sessions. These tests check when no such justification exists: when you have entered no significant information into a website, will the browser still retain data that allows you to be tracked across sessions?)
Alt-SvcAlt-Svc allows the server to indicate to the web browser that a resource should be loaded on a different server. Because this is a persistent setting, it could be used to track users across websites if it is not correctly partitioned.
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2 result, different session: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2 result, different session: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2 result, different session: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
CacheStorageThe Cache API is a content storage mechanism originally introduced to support ServiceWorkers. If the same Cache object is accessible to multiple websites, it can be abused to track users.
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: e917fd3f-2558-42ac-b08f-c6cd639cb554_1p result, different session: e917fd3f-2558-42ac-b08f-c6cd639cb554_1p unsupported: false passed: false test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: a715dfe4-a7ff-4477-929c-50938cc67332_1p, a715dfe4-a7ff-4477-929c-50938cc67332_1p result, different session: a715dfe4-a7ff-4477-929c-50938cc67332_1p, a715dfe4-a7ff-4477-929c-50938cc67332_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: fcb49e69-7fe4-48a9-88b1-353f709309bc_1p result, different session: fcb49e69-7fe4-48a9-88b1-353f709309bc_1p unsupported: false passed: false test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_1p, 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_1p result, different session: 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_1p, 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 79784830-014a-400f-b0f9-624dcd93d540_1p, 79784830-014a-400f-b0f9-624dcd93d540_1p result, different session: 79784830-014a-400f-b0f9-624dcd93d540_1p, 79784830-014a-400f-b0f9-624dcd93d540_1p unsupported: false, false passed: false, false test failed: false, false
write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') result, different session: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: true, true passed: undefined test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: f6eca5e9-57f3-489d-8966-88072f14efaf_1p result, different session: f6eca5e9-57f3-489d-8966-88072f14efaf_1p unsupported: false passed: false test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 4e05b678-bc4e-4360-baca-31ef3e710454_1p, 4e05b678-bc4e-4360-baca-31ef3e710454_1p result, different session: 4e05b678-bc4e-4360-baca-31ef3e710454_1p, 4e05b678-bc4e-4360-baca-31ef3e710454_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_1p, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p result, different session: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
cookie (HTTP)The cookie, first introduced by Netscape in 1994, is a small amount of data stored by your browser on a website's behalf. It has legitimate uses, but it is also the classic cross-site tracking mechanism, and today still the most popular method of tracking users across websites. Browsers can stop cookies from being used for cross-site tracking by either blocking or partitioning them.
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p_http result, different session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p_http unsupported: false passed: false test failed: false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p_http, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p_http result, different session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p_http, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p_http unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p_http result, different session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p_http unsupported: false passed: false test failed: false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: ea753666-dfd7-4095-9d99-607afefef3e0_1p_http, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p_http result, different session: ea753666-dfd7-4095-9d99-607afefef3e0_1p_http, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p_http unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p_http, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p_http result, different session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p_http, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p_http unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_1p_http, aab779e6-85c2-45db-aaaf-3e0fbfa45088_1p_http result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p_http result, different session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p_http unsupported: false passed: false test failed: false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p_http, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p_http result, different session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p_http, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p_http unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_1p_http, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p_http result, different session: 41c27cca-611e-4669-8605-271b8a55bf27_1p_http, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p_http unsupported: false, false passed: false, false test failed: false, false
cookie (JS)The cookie, first introduced by Netscape in 1994, is a small amount of data stored by your browser on a website's behalf. It has legitimate uses, but it is also the classic cross-site tracking mechanism, and today still the most popular method of tracking users across websites. Browsers can stop cookies from being used for cross-site tracking by either blocking or partitioning them.
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p_js result, different session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p_js unsupported: false passed: false test failed: false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p_js, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p_js result, different session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p_js, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p_js unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p_js result, different session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p_js unsupported: false passed: false test failed: false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: ea753666-dfd7-4095-9d99-607afefef3e0_1p_js, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p_js result, different session: ea753666-dfd7-4095-9d99-607afefef3e0_1p_js, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p_js unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p_js, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p_js result, different session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p_js, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p_js unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_1p_js, aab779e6-85c2-45db-aaaf-3e0fbfa45088_1p_js result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p_js result, different session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p_js unsupported: false passed: false test failed: false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p_js, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p_js result, different session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p_js, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p_js unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_1p_js, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p_js result, different session: 41c27cca-611e-4669-8605-271b8a55bf27_1p_js, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p_js unsupported: false, false passed: false, false test failed: false, false
CookieStoreThe Cookie Store API is an alternative asynchronous API for managing cookies, supported by some browsers.
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported result, different session: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported result, different session: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported result, different session: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
CSS cacheCSS stylesheets are cached, and if that cache is shared between websites, it can be used to track users across sites.
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_10098073690289655 result, different session: fake_10098073690289655 unsupported: false passed: false test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_5619373259275924, fake_4676966595710479 result, different session: fake_5619373259275924, fake_4676966595710479 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_2722344781269046 result, different session: fake_2722344781269046 unsupported: false passed: false test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_786815871286175, fake_101910067485389 result, different session: fake_786815871286175, fake_101910067485389 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_3548684124637227, fake_7647875074697708 result, different session: fake_3548684124637227, fake_7647875074697708 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_2079902755928329, fake_21831477733362448 result, different session: fake_7038052567743347, fake_9801225288283035 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_2966056079062589 result, different session: fake_2966056079062589 unsupported: false passed: false test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_6504992795583939, fake_3405676874494703 result, different session: fake_6504992795583939, fake_3405676874494703 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_8380321634890029, fake_6349335762765322 result, different session: fake_1629142550705165, fake_9002262793635534 unsupported: false, false passed: true, true test failed: false, false
favicon cacheA favicon is an icon that represents a website, typically shown in browser tab and bookmarks menu. If the favicon cache is not partitioned, it can be used to track users across websites.
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
fetch cacheWhen a resource is received via the Fetch API, it is frequently cached. That cache can potentially be abused for cross-site tracking.
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 2, 2 result, different session: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
font cacheWeb fonts are sometimes stored in their own cache, which is vulnerable to being abused for cross-site tracking.
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
iframe cacheAn iframe is an element in a web page than allows websites to embed a second web page. Caching of this web page could be abused for cross-site tracking.
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
image cacheCaching of images in web browsers is a standard behavior. But if that cache leaks between websites, it can be abused for cross-site tracking.
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
indexedDBThe IndexedDB API exposes a transactional database to web pages. That database can be used to track users across websites, unless it is partitioned.
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p result, different session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p unsupported: false passed: false test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p result, different session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p result, different session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p unsupported: false passed: false test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: ea753666-dfd7-4095-9d99-607afefef3e0_1p, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p result, different session: ea753666-dfd7-4095-9d99-607afefef3e0_1p, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p result, different session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_1p, aab779e6-85c2-45db-aaaf-3e0fbfa45088_1p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p result, different session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p unsupported: false passed: false test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p result, different session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p unsupported: false, false passed: false, false test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_1p, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p result, different session: 41c27cca-611e-4669-8605-271b8a55bf27_1p, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p unsupported: false, false passed: false, false test failed: false, false
localStorageThe localStorage API gives websites access to a key-value database that will remain available across visits. If the localStorage API is not partitioned or blocked, it can also be used to track users across websites.
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p result, different session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_1p unsupported: false passed: false test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p result, different session: b9d69397-0be5-4ad8-90d9-a64a42960144_1p, 30b4f094-40c4-4f52-8ba6-602c6c769671_1p unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p result, different session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_1p unsupported: false passed: false test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: ea753666-dfd7-4095-9d99-607afefef3e0_1p, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p result, different session: ea753666-dfd7-4095-9d99-607afefef3e0_1p, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_1p unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p result, different session: 01e97d2c-945e-4df5-a88a-810dda46d821_1p, 204811a6-6f23-484d-bedd-53dfcf71e97b_1p unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_1p, aab779e6-85c2-45db-aaaf-3e0fbfa45088_1p result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p result, different session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_1p unsupported: false passed: false test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p result, different session: df3e81cb-19b4-416a-90fe-c8204234c9ce_1p, 9d3914b5-3e7b-46bf-b815-71e61d115873_1p unsupported: false, false passed: false, false test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_1p, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p result, different session: 41c27cca-611e-4669-8605-271b8a55bf27_1p, c42d1b6b-77ad-4bff-9699-387e74608a1e_1p unsupported: false, false passed: false, false test failed: false, false
prefetch cacheA suggests to browsers they should fetch a resource ahead of time and cache it. But if browsers don't partition this cache, it can be used to track users across websites.
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
Web SQL DatabaseThe Web SQL Database is a deprecated web API for storing data in an SQL database.
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated unsupported: true passed: undefined test failed: false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated unsupported: true passed: undefined test failed: false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated unsupported: true passed: undefined test failed: false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
XMLHttpRequest cacheSimilar to the newer Fetch API, any resource received may be cached by the browser. The cache is potentially vulnerable to cross-site tracking attack.
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
Cross-session third-party tracking tests Which browsers prevent third-party trackers from tracking you across browser sessions?
A common vulnerability of web browsers is that they allow third-party trackers to 'tag' your browser with some tracking data. This tag can be used to re-identify you when you return to a website you visited before. This category of leaks can be prevented by browser if they clean or isolate data between browser sessions. (In cases where a user has logged into a website or entered detailed information, it may be justifiable for a browser to retain information across sessions. These tests check when no such justification exists: when you have entered no significant information into a website, will the browser still retain data that allows you to be tracked across sessions?)
Alt-SvcAlt-Svc allows the server to indicate to the web browser that a resource should be loaded on a different server. Because this is a persistent setting, it could be used to track users across websites if it is not correctly partitioned.
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2 result, different session: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2 result, different session: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2 result, different session: h2 unsupported: true passed: undefined test failed: false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
write: async () => { // Clear Alt-Svc caching first. let responseText = ""; for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/clear"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after clear:", responseText); // Store "h3" state in Alt-Svc cache for (let i = 0; i < 3; ++i) { await fetch(altSvcOrigin + "/set"); await sleepMs(100); } responseText = await fetchText(altSvcOrigin + "/protocol"); console.log("after set:", responseText); } read: async () => { const protocol = await fetchText(altSvcOrigin + "/protocol"); if ((new URL(location)).searchParams.get("thirdparty") === "same") { if (protocol !== "h3") { throw new Error("Unsupported"); } } return protocol; } result, same session: h2, h2 result, different session: h2, h2 unsupported: true, true passed: undefined test failed: false, false
CacheStorageThe Cache API is a content storage mechanism originally introduced to support ServiceWorkers. If the same Cache object is accessible to multiple websites, it can be abused to track users.
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: e917fd3f-2558-42ac-b08f-c6cd639cb554_3p result, different session: e917fd3f-2558-42ac-b08f-c6cd639cb554_3p unsupported: false passed: false test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: a715dfe4-a7ff-4477-929c-50938cc67332_3p, a715dfe4-a7ff-4477-929c-50938cc67332_3p result, different session: a715dfe4-a7ff-4477-929c-50938cc67332_3p, a715dfe4-a7ff-4477-929c-50938cc67332_3p unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: fcb49e69-7fe4-48a9-88b1-353f709309bc_3p result, different session: fcb49e69-7fe4-48a9-88b1-353f709309bc_3p unsupported: false passed: false test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_3p, 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_3p result, different session: 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_3p, 895b0837-dbb7-43a2-a447-2bf0b69b0fe5_3p unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 79784830-014a-400f-b0f9-624dcd93d540_3p, 79784830-014a-400f-b0f9-624dcd93d540_3p result, different session: 79784830-014a-400f-b0f9-624dcd93d540_3p, 79784830-014a-400f-b0f9-624dcd93d540_3p unsupported: false, false passed: false, false test failed: false, false
write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') result, different session: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: true, true passed: undefined test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: f6eca5e9-57f3-489d-8966-88072f14efaf_3p result, different session: f6eca5e9-57f3-489d-8966-88072f14efaf_3p unsupported: false passed: false test failed: false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 4e05b678-bc4e-4360-baca-31ef3e710454_3p, 4e05b678-bc4e-4360-baca-31ef3e710454_3p result, different session: 4e05b678-bc4e-4360-baca-31ef3e710454_3p, 4e05b678-bc4e-4360-baca-31ef3e710454_3p unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { try { let cache = await caches.open("supercookies"); cache.addAll([`test.css?key=${key}`]); } catch (e) { throw new Error("Unsupported"); } } read: async () => { let cache = await caches.open("supercookies"); let cacheKeys = await cache.keys(); let url = cacheKeys[0].url; return (new URL(url)).searchParams.get("key"); } result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_3p, c42d1b6b-77ad-4bff-9699-387e74608a1e_3p result, different session: Error: undefined is not an object (evaluating 'cacheKeys[0].url'), Error: undefined is not an object (evaluating 'cacheKeys[0].url') unsupported: false, false passed: true, true test failed: false, false
cookie (HTTP)The cookie, first introduced by Netscape in 1994, is a small amount of data stored by your browser on a website's behalf. It has legitimate uses, but it is also the classic cross-site tracking mechanism, and today still the most popular method of tracking users across websites. Browsers can stop cookies from being used for cross-site tracking by either blocking or partitioning them.
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: null result, different session: null unsupported: true passed: undefined test failed: false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: null result, different session: null unsupported: true passed: undefined test failed: false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: null result, different session: null unsupported: true passed: undefined test failed: false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: async (secret) => { // Request a page that will send an HTTPOnly 'set-cookie' response header with secret value. await fetch(`${baseURI}cookie?secret=${secret}_http`); } read: async () => { // Test if we now send a requests with a 'cookie' header containing the secret. let response = await fetch(`${baseURI}headers`); let cookie = (await response.json())["cookie"]; return cookie ? cookie.match(/secret=([\w-]+)/)[1]: null; } result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
cookie (JS)The cookie, first introduced by Netscape in 1994, is a small amount of data stored by your browser on a website's behalf. It has legitimate uses, but it is also the classic cross-site tracking mechanism, and today still the most popular method of tracking users across websites. Browsers can stop cookies from being used for cross-site tracking by either blocking or partitioning them.
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: null result, different session: null unsupported: true passed: undefined test failed: false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: null result, different session: null unsupported: true passed: undefined test failed: false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: null result, different session: null unsupported: true passed: undefined test failed: false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
write: (secret) => { document.cookie = `secret=${secret}_js; max-age=3600; SameSite=None; Secure`; } read: () => document.cookie ? document.cookie.match(/secret=([\w-]+)/)[1] : null result, same session: , result, different session: , unsupported: true, true passed: undefined test failed: false, false
CookieStoreThe Cookie Store API is an alternative asynchronous API for managing cookies, supported by some browsers.
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported result, different session: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported result, different session: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported result, different session: Error: Unsupported unsupported: true passed: undefined test failed: false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
write: (data) => { const msPerHour = 60 * 60 * 1000; if (!window.cookieStore) { throw new Error("Unsupported"); } window.cookieStore.set({ name: "partition_test", value: data, expires: Date.now() + msPerHour, sameSite: "none" }); } read: async () => { if (!window.cookieStore) { throw new Error("Unsupported"); } const cookie = await window.cookieStore.get("partition_test"); if (!cookie) { return null; } return cookie.value; } result, same session: Error: Unsupported, Error: Unsupported result, different session: Error: Unsupported, Error: Unsupported unsupported: true, true passed: undefined test failed: false, false
CSS cacheCSS stylesheets are cached, and if that cache is shared between websites, it can be used to track users across sites.
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_5905733403402953 result, different session: fake_5905733403402953 unsupported: false passed: false test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_9212160998643075, fake_21315202256079435 result, different session: fake_9212160998643075, fake_21315202256079435 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_9505410302349433 result, different session: fake_9505410302349433 unsupported: false passed: false test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_6414078524540181, fake_9480236535673481 result, different session: fake_6414078524540181, fake_9480236535673481 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_9223366455514792, fake_3397653525982789 result, different session: fake_9223366455514792, fake_3397653525982789 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_10757438605778114, fake_7119310657100273 result, different session: fake_911598417867393, fake_38567970837494014 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_14895157612778376 result, different session: fake_14895157612778376 unsupported: false passed: false test failed: false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_5245499299808889, fake_7522348529317842 result, different session: fake_5245499299808889, fake_7522348529317842 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return key; } read: async (key) => { const href = testURI("resource", "css", key); const head = document.getElementsByTagName("head")[0]; head.innerHTML += `<link type="text/css" rel="stylesheet" href="${href}">`; const testElement = document.querySelector("#css"); let fontFamily; while (true) { await sleepMs(100); fontFamily = getComputedStyle(testElement).fontFamily; if (fontFamily.startsWith("fake")) { break; } } console.log(fontFamily); return fontFamily; } result, same session: fake_17956134371792998, fake_10376781350442665 result, different session: fake_503905475027667, fake_6749139913466771 unsupported: false, false passed: true, true test failed: false, false
favicon cacheA favicon is an icon that represents a website, typically shown in browser tab and bookmarks menu. If the favicon cache is not partitioned, it can be used to track users across websites.
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => key read: async (key) => { // Wait for the favicon to load (defined in supercookies.html) await sleepMs(2000); let response = await fetch( testURI("ctr", "favicon", key), {"cache": "reload"}); let count = (await response.text()).trim(); if (count === "0") { throw new Error("No requests received"); } return count; } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
fetch cacheWhen a resource is received via the Fetch API, it is frequently cached. That cache can potentially be abused for cross-site tracking.
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 2, 2 result, different session: 3, 3 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); return key; } read: async (key) => { let response = await fetch(testURI("resource", "fetch", key), {cache: "force-cache"}); let countResponse = await fetch(testURI("ctr", "fetch", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
font cacheWeb fonts are sometimes stored in their own cache, which is vulnerable to being abused for cross-site tracking.
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } body { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); return key; } read: async (key) => { const text = document.createElement("span"); text.id = "text"; text.innerText = "test"; document.body.appendChild(text); const originalWidth = text.getBoundingClientRect().width; let style = document.createElement("style"); style.type='text/css'; let fontURI = testURI("resource", "font", key); style.innerHTML = `@font-face {font-family: "myFont"; src: url("${fontURI}"); } #text { font-family: "myFont" }`; document.getElementsByTagName("head")[0].appendChild(style); let newWidth; do { await sleepMs(100); newWidth = text.getBoundingClientRect().width; } while (newWidth < 0 || newWidth === originalWidth) let response = await fetch( testURI("ctr", "font", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
iframe cacheAn iframe is an element in a web page than allows websites to embed a second web page. Caching of this web page could be abused for cross-site tracking.
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); iframe.addEventListener("load", () => resolve(key), {once: true}); iframe.src = testURI("resource", "page", key); }) read: async (key) => { let iframe = document.createElement("iframe"); document.body.appendChild(iframe); let iframeLoadPromise = new Promise((resolve, reject) => { iframe.addEventListener("load", resolve, {once: true}); }); let address = testURI("resource", "page", key); iframe.src = address; await iframeLoadPromise; let response = await fetch( testURI("ctr", "page", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
image cacheCaching of images in web browsers is a standard behavior. But if that cache leaks between websites, it can be abused for cross-site tracking.
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: (key) => new Promise((resolve, reject) => { let img = document.createElement("img"); document.body.appendChild(img); img.addEventListener("load", () => resolve(key), {once: true}); img.src = testURI("resource", "image", key); }) read: async (key) => { let img = document.createElement("img"); document.body.appendChild(img); let imgLoadPromise = new Promise((resolve, reject) => { img.addEventListener("load", resolve, {once: true}); }); img.src = testURI("resource", "image", key); await imgLoadPromise; let response = await fetch( testURI("ctr", "image", key), {"cache": "reload"}); return (await response.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
indexedDBThe IndexedDB API exposes a transactional database to web pages. That database can be used to track users across websites, unless it is partitioned.
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_3p result, different session: undefined unsupported: false passed: true test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: b9d69397-0be5-4ad8-90d9-a64a42960144_3p, 30b4f094-40c4-4f52-8ba6-602c6c769671_3p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_3p result, different session: undefined unsupported: false passed: true test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: ea753666-dfd7-4095-9d99-607afefef3e0_3p, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_3p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 01e97d2c-945e-4df5-a88a-810dda46d821_3p, 204811a6-6f23-484d-bedd-53dfcf71e97b_3p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_3p, aab779e6-85c2-45db-aaaf-3e0fbfa45088_3p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_3p result, different session: undefined unsupported: false passed: true test failed: false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: df3e81cb-19b4-416a-90fe-c8204234c9ce_3p, 9d3914b5-3e7b-46bf-b815-71e61d115873_3p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
  write: async (secret) => { try { return await IdbKeyVal.set("secret", secret); } catch (e) { throw new Error("Unsupported"); } } read: () => IdbKeyVal.get("secret") result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_3p, c42d1b6b-77ad-4bff-9699-387e74608a1e_3p result, different session: undefined unsupported: false, false passed: true, true test failed: false, false
localStorageThe localStorage API gives websites access to a key-value database that will remain available across visits. If the localStorage API is not partitioned or blocked, it can also be used to track users across websites.
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 4b038f66-3d96-490d-9033-f44e8bd89b5a_3p result, different session: null unsupported: false passed: true test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: b9d69397-0be5-4ad8-90d9-a64a42960144_3p, 30b4f094-40c4-4f52-8ba6-602c6c769671_3p result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: dc14e90f-d0e6-4b28-8bee-6c87ecdfe134_3p result, different session: null unsupported: false passed: true test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: ea753666-dfd7-4095-9d99-607afefef3e0_3p, 884e9bef-d44b-4ae8-9dfa-30f475d25e39_3p result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 01e97d2c-945e-4df5-a88a-810dda46d821_3p, 204811a6-6f23-484d-bedd-53dfcf71e97b_3p result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 1c9ce4c5-cd24-4228-9f3e-65e0d5c07311_3p, aab779e6-85c2-45db-aaaf-3e0fbfa45088_3p result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 821273ec-e54c-4c12-9bfe-a0c8834a1bd4_3p result, different session: null unsupported: false passed: true test failed: false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: df3e81cb-19b4-416a-90fe-c8204234c9ce_3p, 9d3914b5-3e7b-46bf-b815-71e61d115873_3p result, different session: , unsupported: false, false passed: true, true test failed: false, false
  write: (secret) => localStorage.setItem("secret", secret) read: () => localStorage.getItem("secret") result, same session: 41c27cca-611e-4669-8605-271b8a55bf27_3p, c42d1b6b-77ad-4bff-9699-387e74608a1e_3p result, different session: , unsupported: false, false passed: true, true test failed: false, false
prefetch cacheA suggests to browsers they should fetch a resource ahead of time and cache it. But if browsers don't partition this cache, it can be used to track users across websites.
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received result, different session: Error: No requests received unsupported: true passed: undefined test failed: false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); return key; } read: async (key) => { let link = document.createElement("link"); link.rel = "prefetch"; link.href = testURI("resource", "prefetch", key); document.getElementsByTagName("head")[0].appendChild(link); await sleepMs(500); let response = await fetch( testURI("ctr", "prefetch", key), {"cache": "reload"}); let countString = (await response.text()).trim(); if (parseInt(countString) === 0) { throw new Error("No requests received"); } return countString; } result, same session: Error: No requests received, Error: No requests received result, different session: Error: No requests received, Error: No requests received unsupported: true, true passed: undefined test failed: false, false
Web SQL DatabaseThe Web SQL Database is a deprecated web API for storing data in an SQL database.
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated unsupported: true passed: undefined test failed: false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated unsupported: true passed: undefined test failed: false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated unsupported: true passed: undefined test failed: false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
write: async (key) => { if (!window.openDatabase) { throw new Error("gported"); } let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let tx = new Promise((resolve) => database.transaction(tx => { tx.executeSql( `CREATE TABLE IF NOT EXISTS cache( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, value TEXT NOT NULL, UNIQUE (name) )`, [], (tx, rs) => {}, (tx, err) => {}); tx.executeSql( `INSERT OR REPLACE INTO cache(name, value) VALUES(?, ?)`, ["secret", key], (tx, rs) => {}, (tx, rs) => {}); })); } read: async () => { let database = window.openDatabase("sqlite_supercookie", "", "supercookie", 1024 * 1024); let result = await new Promise((resolve, reject) => database.transaction(tx => { tx.executeSql( "SELECT value FROM cache WHERE name=?", ["secret"], (tx, rs) => resolve(rs), (tx, err) => reject(err)); })); return result.rows.item(0).value; } result, same session: Error: Web SQL is deprecated, Error: Web SQL is deprecated result, different session: Error: Web SQL is deprecated, Error: Web SQL is deprecated unsupported: true, true passed: undefined test failed: false, false
XMLHttpRequest cacheSimilar to the newer Fetch API, any resource received may be cached by the browser. The cache is potentially vulnerable to cross-site tracking attack.
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1 result, different session: 1 unsupported: false passed: false test failed: false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 1, 1 unsupported: false, false passed: false, false test failed: false, false
  write: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; return key; } read: async (key) => { const req = new XMLHttpRequest(); const loadPromise = new Promise(resolve => req.addEventListener("load", resolve)); req.open("GET", testURI("resource", "xhr", key)); req.send(); await loadPromise; let countResponse = await fetch(testURI("ctr", "xhr", key), {cache: "reload"}); return (await countResponse.text()).trim(); } result, same session: 1, 1 result, different session: 2, 2 unsupported: false, false passed: true, true test failed: false, false