Makes a website visitor identifier from a browser fingerprint. Unlike cookies and local storage, fingerprint stays the same in incognito/private mode and even when browser data is purged.

<script>
  function initFingerprintJS() {
    FingerprintJS.load().then(fp => {
      // The FingerprintJS agent is ready.
      // Get a visitor identifier when you'd like to.
      fp.get().then(result => {
        // This is the visitor identifier:
        const visitorId = result.visitorId;
        console.log(visitorId);
      });
    });
  }
</script>
<script
  async
  src="//cdn.jsdelivr.net/npm/@fingerprintjs/fingerprintjs@3/dist/fp.min.js"
  onload="initFingerprintJS()"
></script>

npm i @fingerprintjs/fingerprintjs
# or
yarn add @fingerprintjs/fingerprintjs

import FingerprintJS from '@fingerprintjs/fingerprintjs';

(async () => {
  // We recommend to call `load` at application startup.
  const fp = await FingerprintJS.load();

  // The FingerprintJS agent is ready.
  // Get a visitor identifier when you'd like to.
  const result = await fp.get();

  // This is the visitor identifier:
  const visitorId = result.visitorId;
  console.log(visitorId);
})();

📕 Full documentation

	Open Source version	Pro version
Identification accuracy	60%	99.5%
Bot detection	❌	✅
Incognito / Private mode detection	❌	✅
Geolocation	❌	✅
Security	❌	✅
Server API	❌	✅
Webhooks	❌	✅

Pro result example:

{
  "requestId": "HFMlljrzKEiZmhUNDx7Z",
  "visitorId": "kHqPGWS1Mj18sZFsP8Wl",
  "visitorFound": true,
  "incognito": false,
  "bot": { "probability": 0.96 },
  "browserName": "Chrome",
  "browserVersion": "85.0.4183",
  "os": "Mac OS X",
  "osVersion": "10.15.6",
  "device": "Other",
  "ip": "192.65.67.131",
  "ipLocation": {
    "accuracyRadius": 100,
    "latitude": 37.409657,
    "longitude": -121.965467
    // ...
  }
}

🍿 Live demo

⏱ How to upgrade from Open Source to Pro in 30 seconds

📕 FingerprintJS Pro documentation

The library is shipped in various formats:

• Global variable

  <script>
    function initFingerprintJS() {
      // ...
    }
  </script>
  <script
    async
    src="//cdn.jsdelivr.net/npm/@fingerprintjs/fingerprintjs@3/dist/fp.min.js"
    onload="initFingerprintJS()"
  ></script>

• UMD

  require(
    ['//cdn.jsdelivr.net/npm/@fingerprintjs/fingerprintjs@3/dist/fp.umd.min.js'],
    (FingerprintJS) => {/* ... */}
  );

• ECMAScript module

  import FingerprintJS from '@fingerprintjs/fingerprintjs';

• CommonJS

  const FingerprintJS = require('@fingerprintjs/fingerprintjs');

• FingerprintJS.load({ delayFallback?: number }): Promise<Agent>

  Builds an instance of Agent and waits a delay required for a proper operation. delayFallback is an optional parameter that sets duration (milliseconds) of the fallback for browsers that don't support requestIdleCallback; it has a good default value which we don't recommend to change.

• agent.get({ debug?: boolean }): Promise<{ visitorId: string, components: {/* ... */} }>

  Gets the visitor identifier. debug: true prints debug messages to the console. visitorId is the visitor identifier. components is a dictionary of components that have formed the identifier; each value is an object like { value: any, duration: number } in case of success and { error: object, duration: number } in case of an unexpected error during getting the component.

• FingerprintJS.hashComponents(components: object): string

  Converts a dictionary of components (described above) into a short hash string a.k.a. a visitor identifier. Designed for extending the library with your own components.

• FingerprintJS.componentsToDebugString(components: object): string

  Converts a dictionary of components (described above) into human-friendly format.

• Migration guide
• V2 documentation

The library doesn't guarantee the same visitor identifier between versions, but will try to keep them the same as much as possible.

The documented JS API follows Semantic Versioning. Use undocumented features at your own risk.

npx browserslist "> 1% in us"

See the contribution guidelines to learn how to start a playground, test and build.