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FingerprintJS is a browser fingerprinting library that queries browser attributes and computes a hashed visitor identifier from them. Unlike cookies and local storage, a fingerprint stays the same in incognito/private mode and even when browser data is purged.

View Our Demo.

Quick start

  // Initialize the agent at application startup.
  const fpPromise = import('')
    .then(FingerprintJS => FingerprintJS.load())

  // Get the visitor identifier when you need it.
    .then(fp => fp.get())
    .then(result => {
      // This is the visitor identifier:
      const visitorId = result.visitorId

Run this code

📕 Full documentation

Upgrade to the Pro version to get 99.5% identification accuracy

FingerprintJS Pro is a professional visitor identification service that processes all information server-side and transmits it securely to your servers using server-to-server APIs. Pro combines browser fingerprinting with vast amounts of auxiliary data (IP addresses, time of visit patterns, URL changes and more) to be able to reliably deduplicate different users that have identical devices, resulting in the 99.5% identification accuracy.

Pro plans start at $0/month - no credit card required.

Pro screenshot

Full product comparison:

Open Source Pro

Core Features

100% Open-sourceyesno1
Standard fingerprint signals
screen, os, device name
Advanced fingerprint signals
canvas, audio, fonts
ID typefingerprintvisitorID2
ID lifetimeseveral weeksmonths/years
ID originclientserver
ID collisionscommonrare

Additional Features

Incognito mode detection
works in all modern browsers - see our full list of browsers supported
Server-side accuracy increase
based on additional server-side signals, such as TLS crypto support, ipv4/v6 data and others
Query API & realtime Webhooks
build flexible workflows
based on IP address


Data securityYour infrastructureEncrypted at rest
StorageYour infrastructureUnlimited up to 1 yr
RegionsYour infrastructureHosting in US and EU
ComplianceYour infrastructureGDPR, CCPA compliant3
SLANo SLA99.9% Uptime
SupportGitHub communitySupport team via email, chat, and call-back within 1 business day

1. Pro uses the open source fingerprinting library as well as proprietary technology for increased accuracy and identifier stability.

2. VisitorIDs, in comparison to fingerprints, include server side techniques, are deduplicated and utilize fuzzy matching to result in a more accurate and stable identifier. Fingerprint hashes rely on an exact match across all browser attributes, making them less stable across > 4 week time intervals.

3. FingerprintJS Pro is GDPR and CCPA compliant as the data processor. You still need to be compliant as the data controller and use the identification for fraud under legitimate interest or ask for user consent.

Pro result example:

  "requestId": "HFMlljrzKEiZmhUNDx7Z",
  "visitorId": "kHqPGWS1Mj18sZFsP8Wl",
  "visitorFound": true,
  "confidence": { "score": 0.995 },
  "incognito": false,
  "browserName": "Chrome",
  "browserVersion": "92.0.4515.107",
  "os": "Mac OS X",
  "osVersion": "10.15.6",
  "device": "Other",
  "ip": "",
  "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

▶️ Video: use FingerprintJS Pro to prevent multiple signups

Migrating from v2

Version policy

See the compatibility policy for the API and visitor identifiers in the version policy guide.

Browser support

The library supports all popular browsers. See more details and learn how to run the library in old browsers in the browser support guide.


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

Other products by FingerprintJS