Browser Fingerprinting
·
1 min read
·
109
Words
·
-Views
-Comments
With logged‑in users, identification is trivial. For anonymous users, we can use a browser fingerprint — a unique identifier derived from available device/browser attributes at a point in time. JS doesn’t expose “a fingerprint” directly; you have to compute it (libraries like FingerprintJS help).
FingerprintJS v3
Latest is v4, but v4 uses BSL (becomes MIT after 4 years). In 2024, v4 isn’t MIT yet, so v3 (MIT) is the safe open‑source choice.
Accuracy
- OSS accuracy ~40–60%; commercial ~99.5% (with server‑side components).
- Fingerprints often remain stable only for weeks.
Usage
const fpPromise = new FingerprintJS.load();
fpPromise
.then(fp => fp.get())
.then(result => {
const visitorId = result.visitorId;
console.log(visitorId)
})