Visitor Identification at Scale
Enterprise-ready, GDPR-compliant browser identification - without the enterprise price tag.
Built & priced for volume
Most of this category is priced on the last decimal point of accuracy. That decimal is expensive, and for most uses it changes nothing. We charge a fraction of the going rate for accuracy that covers the large majority of use cases.
Fraud & abuse prevention
Stop new-account fraud and free-trial abuse by recognizing repeat visitors across sessions.
Bot & spam detection
Identify and block automated traffic and spammers with signal-based detection that's hard to spoof.
Cookieless analytics
Track unique visitors and light personalization without relying on cookies or invasive tracking.
Trusted by developers
See ThumbmarkJS in action
Paste this into your browser console to generate your own fingerprint — no install, no signup. See the full output on the demo page.
// just a few lines of code in javascript console
import('https://cdn.jsdelivr.net/npm/@thumbmarkjs/thumbmarkjs/dist/thumbmark.umd.js')
.then(() => {
const tm = new ThumbmarkJS.Thumbmark();
tm.get().then((t) => { console.log(t.thumbmark)})
})
// prints out a 32 character fingerprint like
// 00c8328e409c4831e4aba4f65ec3a0c1Integrate in seconds
Add ThumbmarkJS to your site with just a few lines of code. Works with any framework or plain HTML.
Get API Key
Create a free account to enable server side signals with improved accuracy.
Get API key →Frequently Asked Questions
What is ThumbmarkJS?
ThumbmarkJS is a browser fingerprinting library that calculates a unique identifier based on carefully selected browser, device and HTTP request characteristics. This digital fingerprint, called a thumbmark, is designed to be stable across sessions and resistant to simple anti-fingerprinting techniques.
Your visitorId is an even more stable identifier stored both in the browser and server side, glued together by the thumbmark and some logic. The visitorId is generated by the server side, and is therefore not available in the open source version.
In the open source version, the thumbmark is generated from browser characteristics only. When the API is used, the thumbmark becomes more unique due to the added server-side components.
Who is ThumbmarkJS for?
Three kinds of team use it.
Attribution and adtech. Stitching a visitor's journey across domains, where a third-party cookie no longer survives the hop. Same browser, different domain. This is the heaviest use of the API today.
Fraud and risk. Fake signups from one browser, payment and refund abuse, account takeover, promo abuse, scraping and bots.
Product and growth. Recognizing logged-out returning visitors - persistent carts, metered paywalls, personalization without a cookie.
How accurate is ThumbmarkJS?
How accurate fingerprinting is depends many factors, such as your audience, browser updates, etc. and therefore we cannot guarantee a specific accuracy. However based on our own testing, the open source version has an accuracy of about 80%, and the API increases it to about 99%.
What does ThumbmarkJS cost?
The open source version is completely free. To use the API and the enhanced accuracy it provides, we also offer a free plan with up to 1000 API calls per month. The PRO plan starts at 15€/month and includes 15 000 API calls per month, after which each additional API costs 0.001€. For those who need more than 1 million API calls per month we offer our Enterprise plan, with volume discounts and custom terms. See our pricing page for full details.