Single-signal test
Browser fingerprint test
Every signal below was just read from your browser, locally. Together they form your fingerprint — the cookie that can't be deleted.
Estimated fingerprint entropy
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Measuring in your browser…
The cookie you can't delete
Cookies were the original tracking mechanism, and browsers eventually gave you control over them: you can list them, delete them, block them. Fingerprinting was the industry's answer. Instead of storing an identifier on your machine, a script simply measures your machine — and the measurements are so varied that the combination usually points at exactly one browser: yours. Clear your cookies, go incognito, switch to another Wi-Fi network: the fingerprint survives all of it, because it is recomputed from what your device is, not from what a site stored on it.
The test above runs the same techniques real trackers use — reading your user agent, screen geometry, timezone, language list, then actively probing: drawing a hidden image to hash your graphics stack (canvas), rendering a 3D scene to identify your GPU (WebGL), processing a silent audio signal to fingerprint your sound stack, and measuring text to detect installed fonts. SysLeak shows you each raw value and what it reveals, because seeing your own data is the only way to take the threat seriously.
How identifiable are you?
The entropy figure above is an estimate based on published research, explained step by step on the methodology page. In Eckersley's landmark Panopticlick study, 84% of browsers had a unique fingerprint; among browsers with Flash or Java the figure was 94%. Browsers have improved since — user-agent strings are being frozen, Safari rounds values, Firefox can lie about its hardware — but studies keep finding that the majority of desktop browsers remain uniquely identifiable. If your entropy estimate is above roughly 17 bits, you are likely one of a kind among the visitors of even a very large website.
Frequently asked questions
- What is browser fingerprinting?
- Fingerprinting identifies your browser by combining many small technical attributes — screen size, fonts, GPU, language settings, rendering quirks — into a profile that is often unique. Unlike cookies, there is nothing to delete: the fingerprint is recomputed from your device's own characteristics on every visit.
- What does 'bits of entropy' mean?
- Entropy measures how much identifying information a signal carries. Each bit halves the number of people who match you: 10 bits is roughly one in a thousand, 20 bits one in a million. Around 33 bits would single out one person on the entire internet.
- Can I prevent fingerprinting?
- You can reduce it: Firefox's resistFingerprinting mode, Tor Browser, and Safari's anti-fingerprinting all try to make your browser look like many others. Blocking JavaScript blocks most collection but breaks sites. Paradoxically, exotic privacy tweaks can make you more unique, not less.
- Does SysLeak keep my fingerprint?
- No. Signals are collected and shown in your browser. If aggregate comparison is enabled, only a salted hash and coarse buckets (like browser family) are counted — the raw values never leave your device, and the hash cannot be reversed into them.
This is one signal of many. The SysLeak exposure dashboard combines your IP, fingerprint and WebRTC results into a single Exposure Score.