Browser Privacy Test: Fingerprint & Trackers

A browser fingerprint is the set of technical details your browser reveals to every website: browser and OS version, languages, time zone, screen resolution, installed fonts, graphics card and the tiny differences in how it renders graphics and audio. Each detail is shared by millions of people. Combined, they are often rare — and frequently unique.

Unlike cookies, a fingerprint cannot be wiped with “Clear browsing data”. Cookies are stored on your device; a fingerprint is recomputed every time from how your browser and computer are built. That is why ad networks and anti-fraud systems use fingerprints as a fallback when cookies are unavailable.

The most telling signals depend on hardware and settings. A site can draw an invisible image on a canvas and hash it: different GPUs, drivers and fonts produce slightly different pixels. Audio fingerprinting works the same way — the browser renders a short signal and the result varies slightly between devices.

• Browser, version and operating system.
• Interface languages and time zone, which almost always reveal your country.
• Screen resolution, colour depth, zoom and touch support.
• Installed fonts — office suites and language packs make the list distinctive.
• GPU vendor and model via WebGL.
• CPU core count and device memory.

The bits figure shows how rare your signal combination is. Each bit doubles the number of browsers you can be singled out from: 10 bits is one in a thousand, 20 bits one in a million, 30 bits one in a billion. We estimate entropy from public fingerprinting research and correct for the fact that signals are related. The result is an order of magnitude, not an exact rank: we do not collect a fingerprint database.

Each signal in the table has a status. Exposed means the browser returns the real value. Noise means the value changes between calls — a sign of fingerprinting protection. Hidden means the signal is unavailable. Partial means the browser returns a generic value, such as a GPU without a model name.

Trackers are analytics and advertising scripts embedded on many different sites. When the same tracker sits on thousands of sites, it sees where you go and links your visits by cookie or fingerprint. The test sends requests to several well-known tracker domains from public filter lists and checks whether your browser or extension blocks them.

Third-party cookies are set by an embedded tracker rather than the site you opened. Safari and every browser on iPhone block them by default, and Firefox partitions them per site. Chromium-based browsers allow them by default, which is worth changing in settings.

• Turn on strict tracking protection or install a tracker blocker from the official extension store.
• Block third-party cookies in privacy settings.
• Enable Global Privacy Control if your browser supports it.
• Avoid unnecessary extensions and rare fonts: every unusual signal makes your fingerprint stand out.
• Restrict WebRTC if you do not make calls in the browser.
• Use separate browser profiles for separate tasks so work and personal browsing don’t get linked.

A VPN encrypts your connection and changes the IP address sites see: they get the server’s IP instead of your home IP and city. That matters on public Wi-Fi, in hotels and on other people’s networks, where the network owner and ISP could otherwise see which sites you visit.

A VPN does not change your browser fingerprint, delete cookies or switch off trackers on pages. If you are signed in, the site knows who you are from any IP. Real privacy has two parts: browser settings against trackers and fingerprinting, and an encrypted connection for your IP and traffic.