Browser fingerprinting is a way of recognising a browser by the combined details it reveals, instead of by a cookie it stores. It works even if you clear your cookies, use private mode or change your IP address with a VPN.
How it works
Any website can ask your browser for a long list of harmless facts: your screen resolution, time zone, languages, operating system, the fonts you have installed, how many CPU cores you have, and what graphics card you use. Each is shared by many people. A script also draws hidden images on a canvas or runs a graphics test, and records the output, which differs slightly between devices because of different graphics hardware, drivers and fonts. Combine them and the odds that another browser matches shrink quickly.
Every attribute adds some bits of identifying information. Roughly 33 bits is enough to single out one person among eight billion. Our fingerprint test shows what yours exposes.
Who uses it
- Advertisers and data brokers to follow you across sites when cookies are blocked.
- Fraud-prevention services at banks and shops, to spot a device returning, or a stolen account used from an unfamiliar one. Here the identification protects you.
- Bot-detection systems to tell humans from scripts.
The same technique serves very different purposes, and it is invisible to you either way.
Why it is hard to stop
Many fingerprint signals are things sites legitimately need: screen size for layouts, fonts for text rendering, graphics for games. Blocking them breaks websites. And, paradoxically, hiding or faking details can make you more unusual: a rare combination stands out.
How to reduce your fingerprint
| Approach | How it helps | Cost |
|---|---|---|
| Tor Browser | Makes all users look the same (fixed window size, fonts and spoofed values). | Slower, some sites break. |
| Brave | Randomises canvas, audio and some other outputs per session. | Occasional site issues. |
| Firefox with strict protection | Blocks known fingerprinting scripts; "resistFingerprinting" makes values uniform. | Time zone shows as UTC and sites may misbehave. |
| Safari | Limits many exposed details and blocks known trackers. | Little control. |
| Minimal extensions, default fonts | Fewer unusual traits. | None. |
A VPN does not help here: it changes your IP address, not your browser. For a combined view, run the full privacy scan.
Is it legal?
It is generally legal but regulated. In the EU and UK, reading device information for tracking requires consent under the ePrivacy rules, and the GDPR can apply. In practice enforcement is patchy, and consent banners often cover it.