What Is Browser Fingerprinting?

Browser fingerprinting is a method of tracking users online without using cookies. Instead of storing an identifier on your device, a website collects technical characteristics of your browser and device and turns them into a "fingerprint". Like a real human fingerprint, this digital fingerprint lets a site recognize you across websites and over time, even if you clear your cookies, use private browsing mode or change your IP address.

Every time your web browser loads a page, it shares dozens of data points: browser version, operating system, screen resolution, installed fonts, time zone, language settings, graphics hardware and more. Each attribute on its own is common. Combined into one profile, they often become statistically unique and work as a unique identifier.

How unique is a browser fingerprint in practice? The research gives a range, not one number:

  • 2010, EFF Panopticlick: 83.6% of 470,161 browsers had a unique fingerprint. The sample came from privacy-aware visitors.
  • 2016, AmIUnique: 89.4% of 118,934 fingerprints were unique.
  • 2017, Cao et al.: a technique based on OS and hardware features identified 99.24% of users in a test set of 1,903 devices.
  • 2018, "Hiding in the Crowd": on a large commercial French website, only 33.6% of about 2 million fingerprints were unique.

Fingerprinting is powerful, but its success depends on the audience and on which data points a script collects. For all related checks, see the online privacy check guide.

How Browser Fingerprinting Works

A fingerprinting script runs JavaScript in your browser, reads many attributes and hashes them into one value. The server stores that value and compares it with later visits.

  1. Passive collection. Each request carries HTTP headers, for example the user agent and accepted languages. The server also sees your IP address.
  2. Active collection. JavaScript queries screen size, time zone, CPU cores and the graphics card.
  3. Rendering tests. The script draws hidden text, shapes or 3D scenes, or processes a short audio signal. Small hardware and software differences change the result.
  4. Hashing and matching. All values become one hash. The tracker links that hash to your sessions.

Device fingerprinting is the broader term. It covers the same idea for apps and other devices.

What Data Is Collected for Browser Fingerprinting?

Older fingerprinting methods relied on plugins and the font list. The 2019 survey by Laperdrix et al. notes that plugins have disappeared from major browsers, while canvas became one of the strongest attributes.

Why Do Websites Use Browser Fingerprinting?

Websites use browser fingerprinting for online tracking and for security. Ad and analytics companies use it to track users across sites without cookies. Banks and shops also use fingerprinting to prevent fraud, for example to spot a login from an unknown device.

These tracking techniques are in real use. A 2016 crawl of the top 1 million websites by Princeton researchers found canvas scripts on 14,371 sites and AudioContext scripts on 67 sites.

Does Incognito Mode or a VPN Stop Browser Fingerprinting?

No. Incognito mode deletes cookies after the session, but your fingerprint stays the same, because it is calculated from your device each time. A VPN hides your IP address, yet the fingerprint does not need it. Unlike cookies, nothing is stored that you could delete. Separate browser profiles do not help much either, since they run on the same hardware.

How to Reduce Your Browser Fingerprint

To avoid browser fingerprinting, you either look like many other users or change your values on every site.

Use Brave Browser

Brave has strong built-in protection, on by default. It randomizes canvas and Web Audio output per site and per session. Since version 1.93 (2026) it reports a generic WebGL vendor and renderer string and randomizes the WebGL extension list. It also limits which installed fonts sites can see.

Use Firefox with Privacy Hardening

Enable "Resist Fingerprinting" in about:config: set privacy.resistFingerprinting to true. Firefox then reports UTC, limits fonts to system fonts and adds noise to canvas data. Mozilla warns that this can break sites and recommends the lighter Fingerprinting Protection for most users.

Use the Tor Browser

The Tor Browser applies the strongest fingerprint resistance available. Its design goal is to make all users look the same, for example with a fixed font set and blocked canvas reads.

Use Safari

Safari 26 (2025) prevents known fingerprinting scripts from reliably reading screen dimensions, hardware concurrency, web audio and 2D canvas.

Should You Disable JavaScript?

Disabling JavaScript blocks most active techniques, but many websites stop working. HTTP headers and your IP address stay visible. Browser extensions that block fingerprinting scripts are a middle ground, but each extension also changes your profile.

How Can I Check My Browser Fingerprint?

You can run the SpeedIQ privacy checks directly in your browser. The fingerprint group shows what any website can collect:

SpeedIQ checkWhat it reads
Browser FP (canvas)Draws a short text on a hidden canvas and shows a hash
Screen InfoScreen resolution and color depth
Hardware InfoCPU cores and device memory
Language and TimezoneLanguages, time zone and UTC offset
User Agent, Cookies, DNTBrowser string, cookie status, Do Not Track
Battery, Connection APIBattery status and network type, if exposed

The results stay in your browser. Compare the canvas hash after a browser restart: if it changes on the same device, your browser randomizes canvas output.

Summary

Browser fingerprinting is an invisible, persistent tracking technique that follows you across the web without cookies, often without your consent. To protect your privacy, first see what your browser exposes.

→ Try it free: You can check your browser fingerprint directly at SpeedIQ — no account, no ads.

FAQ

Is browser fingerprinting illegal?

Not in general, but data protection laws regulate it. In the EU, the Article 29 Working Party stated in 2014 that the ePrivacy consent rule (Article 5(3)) applies to device fingerprinting, so trackers usually need your consent.

Does Brave prevent browser fingerprinting?

Brave reduces it by default. It randomizes canvas and audio output per site and session, reports a generic WebGL renderer since version 1.93 and limits visible fonts.

Can I disable browser fingerprinting completely?

No. Every browser shares some data points, such as HTTP headers and your IP address. You can only make your fingerprint less unique or less stable.

Does clearing cookies stop browser fingerprinting?

No. A browser fingerprint is calculated from your browser and device on every visit. Nothing is stored on your device, so there is nothing to delete.

How can I check my browser fingerprint?

Run the SpeedIQ privacy checks on the start page. The fingerprint group shows your canvas hash, screen, hardware, language, time zone and user agent.

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