Testing guide
Is my browser fingerprint unique?
Fingerprint checkers often say “your browser is unique”. That sounds bad, but it is the normal result. This guide explains why, and what you should look at instead.
Direct answer
Probably yes. In the EFF’s Panopticlick study, 83.6% of browsers had a unique fingerprint. Uniqueness alone is not the problem, because so many other browsers are unique too. Sites care more about values that contradict each other, and about many accounts that share one fingerprint. A fingerprint test shows both.
How unique are browsers?
| Study | Sample | Unique |
|---|---|---|
| EFF Panopticlick, 2010 | Visitors of the Panopticlick test site | 83.6%, and 94.2% of browsers with Flash or Java |
| AmIUnique, 2016 | Visitors of the AmIUnique test site | 89.4% |
| Hiding in the Crowd, 2018 | 2,067,942 fingerprints from one of the top 15 French websites | 33.6% |
The share depends on who is measured. Visitors of test sites care about privacy and often have unusual setups. A large general audience has more look-alike devices.
A checker also compares you only with its own visitors. “Unique” there does not mean unique on the whole web. Modern checkers also read more values than the 2010 study, such as canvas and WebGL output.
Which values make a fingerprint unique
- Canvas and WebGL output: the graphics card, driver and fonts change how text and shapes are drawn.
- Graphics card name, as WebGL reports it.
- Installed fonts.
- Screen size and pixel ratio.
- Time zone and language list.
- Browser version and OS.
- CPU core count and device memory.
- Audio output: a rendered sound differs slightly between devices.
Each value alone is common. The combination is rare. That is why one change, such as a new monitor, can give you a new fingerprint.
What matters more than uniqueness
- Inconsistency: values that contradict each other. Examples are a Windows user agent with Mac fonts, a time zone far from the IP, or a graphics card that the OS cannot have.
- Shared fingerprints: two accounts that show the same fingerprint look like one person. A site can link them, even with different IPs.
- Changes between visits: one checker, Iphey, flagged a returning profile whose screen size or GPU changed between visits. Fresh profiles were not flagged.
- Signs of spoofing: built-in functions that a script replaced, or noise that a site can detect.
Our test looks for these problems, not for uniqueness. It fails a check only for a value that a stock browser never shows.
What you can and cannot change
| Value | Can you change it? | Note |
|---|---|---|
| Language list | Yes | Browser language settings. |
| Time zone | Yes | System clock settings. Keep it near your IP location. |
| Fonts | Partly | You can add fonts, but the OS’s own fonts stay. |
| Screen size | Partly | It comes from the monitor and the display scale. |
| Graphics card, canvas, audio | Not in a normal browser | Extensions that change them leave traces that sites can read. |
| TLS fingerprint | No | It comes from the browser engine. |
| Browser version | Yes | Update the browser. |
Random changes on every visit make you unique each time, and the noise itself can be seen. Tor Browser and Mullvad Browser take the other path: they try to make all their users look the same.
If you run several accounts, the goal is different. Each account needs its own fingerprint that is consistent and stays the same on every visit.
Frequently asked questions
Is a unique browser fingerprint bad?
Not by itself. Most desktop browsers are unique on test sites. Values that contradict each other, and one fingerprint shared by several accounts, matter more.
Can I make my fingerprint not unique?
Tor Browser and Mullvad Browser try to make all users look the same. In a normal browser, removing one rare value rarely helps, because the combination stays rare.
Does incognito mode change my fingerprint?
No. Incognito removes cookies and history after the session. The graphics card, fonts, screen and time zone stay the same.
Why does my fingerprint change between tests?
A browser update, a new monitor, a font or a changed setting can change it. Some privacy features also add noise on purpose.