FingerprintJS is the best-known browser fingerprinting library. These are the tools developers compare it with, from open-source libraries that run in your pages to APIs that register identifications and let your server verify them, with prices from each vendor's published pages.
| Tool | What it is | Free | Server-side verification | License |
|---|---|---|---|---|
| TraceTail | Browser fingerprinting API (script tag or npm) | 1,000 requests a month; keyless use is free | Yes: Server API with secret server keys | Hosted service; MIT-licensed SDK |
| Fingerprint (Pro) | Device intelligence platform | 1,000 web API calls a month | Yes: Server API | Commercial |
| FingerprintJS | Open-source browser library | Free: runs in your pages | No: IDs are computed in the browser only | MIT (since 5.0.0) |
| ThumbmarkJS | Open-source library with a paid API | Library free; API 1,000 calls a month | With the API, results are posted to your server afterwards; no lookup | MIT (library) |
| ClientJS | Open-source browser library | Free: runs in your pages | No: IDs are computed in the browser only | Apache-2.0 |
What each hosted API costs at list price for the identification requests a month shown. The open-source libraries cost nothing to run but have no API behind them.
| API | 10,000 a month | 100,000 a month | 1,000,000 a month |
|---|---|---|---|
| TraceTail | $0.90 | $9.90 | $99.90 |
| Fingerprint (Pro) | $99.00 | $419.00 | Custom (Enterprise) |
| ThumbmarkJS | €15 + VAT | €100 + VAT | €1,000 + VAT |
Browser fingerprinting API (script tag or npm)
A stable visitor ID with over 99.5% accuracy, the same in normal and incognito windows, without cookies. The SDK runs keyless with no sign-up; with a key, identifications are registered, checked for automation and verifiable from your server. 1,000 requests are free every month, then $0.10 per 1,000 at every volume.
Choose it when you want an API with server-side verification at a per-request price that stays low at volume, for web apps.
Device intelligence platform
The company behind FingerprintJS. Its Pro Plus plan costs $99.00 a month including 20,000 API calls, then $4.00 per 1,000, with native iOS and Android SDKs and Smart Signals such as VPN and browser-tamper detection. Free and Pro Plus allow 5 requests a second and keep data 30 days.
Choose it when you need native mobile SDKs, VPN or tamper signals, or an enterprise SLA, and the price fits.
Open-source browser library
The best-known library. It is MIT-licensed again since version 5.0.0 (October 22, 2025); 4.x was BUSL-1.1. Its README says its accuracy is "significantly lower than in the commercial version" and that, being computed in the browser, "they are vulnerable to spoofing and reverse engineering".
Choose it when you only need a rough in-browser hash, with nothing to verify on a server.
Open-source library with a paid API
Its README puts the browser library at ~80% uniqueness and its API at ~99%. The Pro API plan costs €15 a month including 15,000 calls, then €1 per 1,000, excluding VAT.
Choose it when you want an MIT library you can run yourself, with an optional API priced in euros.
Open-source browser library
Hashes browser traits, including the user agent, into a 32-bit number. Its last release is 0.2.1, from October 25, 2021.
Choose it when you maintain a legacy integration that already depends on it.
List prices from each vendor's pricing page as of October 5, 2026 (ThumbmarkJS's exclude VAT). Accuracy and uniqueness figures are each vendor's own claims.
1,000 requests free every month, no credit card required. Add a card only when you need more.