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Fingerprinting

Browser fingerprint

Also called browser fingerprinting, device fingerprint, device fingerprinting, digital fingerprint

Definition

A browser fingerprint is the combination of values a website can read from your browser and device without storing anything, such as the user agent, screen size, time zone, fonts and graphics card, which together can tell one browser from another.

Last updated 7 November 2026

How it works

Every page can run JavaScript, and that script can ask the browser a lot of questions: which browser and version it is, the operating system, the screen size, the number of CPU cores, the time zone and languages, which fonts render, the graphics card’s name, and what an image or a sound comes out as when the device processes it. The server adds what arrives with the request: the IP address, the headers and the shape of the TLS handshake.

None of these is unique on its own. Combined, they often are. Peter Eckersley’s 2010 study for the EFF found that most browsers in its sample could be told apart by their fingerprint alone, with no cookie at all. Unlike a cookie, a fingerprint can’t be deleted, because it is read fresh from the device every time.

Why it matters when you run several accounts

Two accounts used from the same browser on the same computer present the same fingerprint, so a site can connect them even when their cookies are separate. Consistency matters as much as difference. A profile whose values contradict each other, such as a Windows user agent with macOS fonts, or a New York time zone on a German IP address, stands out more than an ordinary one.

How SoftGlaze Browser handles it

Each profile gets its own generated device, set on the Fingerprint tab in 4 groups: core identity, hardware noise and graphics, hardware configuration, and advanced settings. On the standard engine the WebGL image, AudioContext, ClientRects and SpeechVoices results differ per profile; a flat 2D canvas drawing still returns your computer’s real result there, and only the optional fingerprint-chromium engine changes it. Leak Check compares a profile’s values, scores them out of 100, and its live test reads what the running browser really reports.

Sources

  1. How Unique Is Your Web Browser? (Eckersley, 2010)Electronic Frontier Foundation
  2. Mitigating Browser Fingerprinting in Web SpecificationsW3C
  3. Cover Your TracksElectronic Frontier Foundation

Outside sources were checked in November 2026. Browsers, standards and vendors' pages change, so details that depend on them are as of that month.

Related terms

  • Canvas fingerprintingCanvas fingerprinting is a technique in which a page draws hidden text and shapes on an HTML canvas, reads the pixels back and hashes them, because the exact result depends on the device's graphics hardware, drivers, fonts and operating system.
  • WebGL fingerprintA WebGL fingerprint is what a site learns from the browser's 3D graphics interface: the graphics card and driver names it reports, its limits and supported extensions, and the exact pixels it produces when it renders a test scene.
  • User agentA user agent string is the line of text a browser sends with every request, and shows to scripts, naming the browser, its version, the rendering engine and the operating system.
  • Timezone mismatchA timezone mismatch is when the time zone a browser reports does not fit the location of the IP address it connects from, for example a browser on London time arriving from a New York address.
  • Account linkingAccount linking is when a platform concludes that two or more accounts are run by the same person or device, by matching traces they share, such as cookies, device fingerprints, IP addresses, payment details or behaviour.

Read more on this site

See it in SoftGlaze Browser

Separate profiles, each with its own cookies, device values and proxy, on Windows. Try the app's screens in your browser first, or start the free trial; no card needed.

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