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. Demo.

Quick start

Install from CDN

<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>

Alternatively you can install from NPM to use with Webpack/Rollup/Browserify

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

Upgrade to Pro version to get 99.5% identification accuracy

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

Pro result example:

{
  "requestId": "HFMlljrzKEiZmhUNDx7Z",
  "visitorId": "kHqPGWS1Mj18sZFsP8Wl",
  "visitorFound": true,
  "incognito": false,
  "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

Open-source version reference

Installation

The library is shipped in various formats:

• Global variable

  <script>
    function initFingerprintJS() {
      // Start loading FingerprintJS here
    }
  </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) => {
      // Start loading FingerprintJS here
    }
  );

• ECMAScript module

  # Install the package first:
  npm i @fingerprintjs/fingerprintjs
  # or
  yarn add @fingerprintjs/fingerprintjs

  import FingerprintJS from '@fingerprintjs/fingerprintjs';
  
  // Start loading FingerprintJS here

• CommonJS

  # Install the package first:
  npm i @fingerprintjs/fingerprintjs
  # or
  yarn add @fingerprintjs/fingerprintjs

  const FingerprintJS = require('@fingerprintjs/fingerprintjs');
  
  // Start loading FingerprintJS here

API

• 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.

Migrating from v2

• Migration guide
• V2 documentation

Version policy

The OSS version doesn't guarantee the same visitor identifier between versions, but will try to keep them the same as much as possible. To get identifiers that remain stable up to 1 year, please consider upgrading to pro.

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

Browser support

npx browserslist "cover 95% in us, not IE < 10"

See more details and learn how to run the library in old browsers in the documentation article.

Contributing

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