Browser Fingerprinting: What It Is and How to Reduce It
Clearing cookies feels like a fresh start, but a website can often still recognize your browser. The technique is called fingerprinting, and it works by reading ordinary settings and capabilities that every browser exposes.
The idea in one paragraph
No single detail about your browser is unique. Lots of people use the same browser version, the same screen size or the same language. Put dozens of such details together, though, and the combination can be rare enough to pick you out of a crowd. A script collects the details, mixes them into a short hash, and compares it with the hash it saw before. If it matches, it is probably the same browser, with no cookie required.
What gets measured
| Signal | What it is | Why it varies between people |
|---|---|---|
| User agent and client hints | Browser, version and operating system. | Many version and platform combinations. |
| Screen and window | Resolution, color depth, pixel ratio, available area. | Monitors, laptops and scaling settings differ. |
| Time zone and language | Your locale, number and date formats. | Combinations of region and language preferences. |
| Fonts | Which typefaces are installed. | Software, languages and operating systems add fonts. |
| Canvas | How the browser draws a hidden image. | Graphics hardware, drivers and font rendering produce slightly different pixels. |
| WebGL | Graphics card and driver details. | GPU model and driver version. |
| Audio | How the audio engine processes a test signal. | Audio stack and hardware differences. |
| Hardware | CPU thread count, memory hint, touch support. | Device model and configuration. |
| Features and storage | Which APIs and storage types are available. | Browser version, settings and extensions. |
The GotInfo fingerprint page reads these categories in your own browser and combines them into a hash, so you can see what a script on any site could collect. Marking each group as common or unique gives a rough sense of which signals make you stand out. The checks run in your browser, and GotInfo does not store the results.
Why sites do it
Some uses are protective. Banks and online stores use fingerprints to spot account takeover and fraud, and many services use them to detect automated traffic. Others are about advertising: stitching together a person's activity across sites when cookies are blocked or cleared. The same technique serves both, which is why it is hard to ban outright and hard to opt out of.
What does not help
- Clearing cookies. A fingerprint is built from the browser itself, not from stored data.
- Private or incognito windows. They avoid saving history and cookies, but the browser exposes the same properties.
- A VPN on its own. It changes your IP address, not your screen, fonts or graphics hardware.
- Piling on privacy extensions. Each unusual extension can make your setup rarer, and therefore easier to recognize.
What does help
- Blend in. Tor Browser aims to make all its users look alike, using standard window sizes and limiting what scripts can read. This is the strongest approach, with some loss of convenience.
- Use a browser with built-in protections. Firefox can block known fingerprinting scripts in Enhanced Tracking Protection and offers a stricter resist-fingerprinting setting. Brave randomizes some values such as canvas and audio output on each session. Safari limits some of the information it exposes.
- Keep your browser current and fairly standard. Common versions on common platforms are harder to single out than outdated ones with unusual settings.
- Limit extensions and font installs. Fewer unusual additions mean fewer distinguishing details.
- Avoid resizing the window to odd sizes when you use a browser that aims for uniformity.
- Separate identities. Use different browsers or profiles for different purposes, so one fingerprint does not connect everything you do.
Blending versus randomizing
There are two philosophies. One tries to make everyone look the same, so a fingerprint tells a site nothing special. The other changes the answers so that the fingerprint keeps shifting and cannot be matched from one visit to the next. Both help, but neither is perfect, and both can break the odd site that relies on exact values. Pick the trade-off that suits how you use the web, and re-test after major updates, as browsers change what they expose.
See your own result: open the GotInfo fingerprint tool, then try a different browser or settings to compare the hashes.