Browser fingerprinting is a tracking technique that identifies you across websites by collecting dozens of signals from your browser and device — without storing a single cookie. Even in private browsing mode, your fingerprint stays the same. You can see how unique yours is right now on whatsmy.fyi.
What Is a Browser Fingerprint?
A browser fingerprint is a unique profile built from the combination of your browser's settings, your device's hardware characteristics, and your software environment. No single piece of data identifies you — but the combination of 30 or more signals is often unique enough to distinguish one user from millions of others.
The term comes from forensic fingerprinting: just as no two people share identical fingerprints, no two browser configurations are exactly alike. The technique was first described academically by the Electronic Frontier Foundation (EFF) in 2010, and it is now used by advertisers, fraud-prevention systems, and analytics platforms worldwide.
What Signals Make Up a Browser Fingerprint?
Fingerprinting scripts typically collect a combination of the following:
- User agent string: Your browser name, version, operating system, and rendering engine (e.g., Chrome 124 on Windows 11). See the user agent guide for more detail.
- Screen resolution and colour depth: The pixel dimensions and colour support of your display.
- Timezone and language settings: Your browser's configured locale and the offset between your local time and UTC.
- Installed fonts: Your system's installed font list, measured by rendering speed differences across known fonts.
- Canvas fingerprint: A hidden HTML5 canvas element renders a complex shape. Subtle differences in GPU, drivers, and anti-aliasing produce a pixel pattern unique to your device.
- WebGL renderer: The name and version of your graphics card and driver, exposed via the WebGL API.
- Audio fingerprint: How your device's audio stack processes a synthetic tone — hardware differences produce measurable variation.
- Hardware concurrency: The number of logical CPU cores your device reports.
- Touch support and device memory: Whether your screen is a touchscreen and how much RAM your device reports (capped at 8 GB for privacy).
- Browser plugins and features: Which web APIs your browser supports, and in some cases which extensions you have installed.
How Unique Is Your Fingerprint?
The EFF's research found that over 83% of browsers have a fingerprint unique enough to identify them from a database of millions. More recent studies put that figure even higher as devices become more varied.
whatsmy.fyi calculates a uniqueness score by hashing a combination of canvas output, WebGL renderer string, screen dimensions, timezone, language, hardware concurrency, touch support, and colour depth. The "1 in ~N" figure tells you roughly how many browsers share your exact configuration.
How Is Fingerprinting Different from Cookies?
Cookies are stored on your device — you can delete them, block them, or view them in your browser settings. Browser fingerprinting requires no storage on your device at all. The server builds the identifier from data your browser freely transmits with every request.
This makes fingerprinting significantly harder to block. Clearing your cache, using incognito mode, or switching to a private search engine has no effect on your fingerprint. Only changing your browser, OS, device, or explicitly randomising these signals can break continuity.
Is Browser Fingerprinting Legal?
In many jurisdictions, fingerprinting falls into a legal grey area. Under GDPR in Europe, fingerprinting is considered processing of personal data when it can reasonably identify a natural person — which it typically can. This means it requires a valid legal basis (consent, legitimate interest, etc.) and must be disclosed in a privacy policy.
In practice, enforcement is inconsistent. Many sites use fingerprinting under the guise of "fraud prevention" — a use case that generally qualifies under legitimate interest — without obtaining explicit consent.
How Can You Reduce Your Fingerprint?
Complete prevention is difficult, but there are practical steps:
- Use Brave Browser: Brave randomises many fingerprinting signals per session, making tracking across sites unreliable.
- Use Firefox with privacy settings: Firefox with
privacy.resistFingerprintingenabled normalises many signals to a common value. - Use the Tor Browser: Tor normalises all fingerprinting signals to a common baseline — every Tor user looks the same to tracking scripts.
- Avoid installing unusual fonts or extensions: Rare fonts and uncommon extension sets make your browser more unique, not less.
- Use a VPN: A VPN changes your IP address, removing one layer of the fingerprint. But it does not affect canvas, WebGL, or audio signals. Check whether your VPN is working on whatsmy.fyi.
Frequently Asked Questions
Does private/incognito mode prevent fingerprinting?
No. Private mode prevents your browser from saving history, cookies, and form data locally. It does not change your canvas output, screen resolution, GPU, or any other fingerprinting signal. Sites can still build an identical fingerprint in incognito mode.
Can a VPN stop browser fingerprinting?
A VPN masks your IP address but does not affect the hardware and software signals that make up your fingerprint. It is one useful layer of privacy, but insufficient on its own. See the VPN detection guide for more on how VPNs are identified.
Is browser fingerprinting the same as tracking pixels?
No. Tracking pixels are tiny invisible images embedded in emails or web pages that confirm delivery. Browser fingerprinting is a JavaScript-based technique that actively probes your device capabilities. They are distinct tracking mechanisms, though often used together.
What is canvas fingerprinting specifically?
Canvas fingerprinting works by drawing a hidden image using HTML5 Canvas API. Tiny differences in GPU hardware, graphics drivers, and OS font rendering cause the pixel output to vary slightly between devices. This variation is hashed into a stable identifier that is extremely hard to fake without changing your hardware.
