You delete cookies, use incognito mode, and block trackers. But ads still show the product you searched for yesterday. How do they know? The answer may not be cookies, but browser fingerprinting: a tracking technique that is much harder to avoid. Browser fingerprinting collects technical information about your browser and device: screen resolution, installed fonts, time zone, language, browser version, active plugins, and dozens of other parameters. Combined, these parameters produce a unique profile that can distinguish you from millions of other internet users, without storing anything on your device.
Why browser fingerprinting is hard to avoid
Unlike cookies stored in your browser that can be deleted, browser fingerprinting works on the server side. Websites collect information your browser sends automatically when loading pages. You cannot "delete" your screen resolution or installed font list. Studies show that 80-90% of browsers have unique fingerprints. This means even if you are not logged in, use a VPN, or delete cookies, websites can still recognize your browser from visit to visit.
Information collected for fingerprinting
Websites can collect dozens of parameters, including:
- User agent: browser version, operating system, device architecture
- Screen resolution and color depth: monitor size and display settings
- Time zone and language: general location and language preferences
- Installed fonts: the font list on your system can be unique
- Plugins and extensions: list of active plugins
- Canvas fingerprint: how your browser renders 2D graphics, which differs across devices due to hardware and driver differences
- WebGL fingerprint: information about your graphics card and rendering capabilities
- Audio fingerprint: how your device processes audio, which is also unique
- Battery status: battery level and charging state (restricted in modern browsers)
- CPU cores: number of processor cores
7 ways to reduce your browser fingerprint
1. Use browsers that protect against fingerprinting
Some browsers have built-in protections:
- Firefox with Enhanced Tracking Protection blocks fingerprinting scripts
- Brave actively randomizes fingerprint values to make you look like other users
- Tor Browser equalizes all users' fingerprints, making you indistinguishable Chrome has limited fingerprinting protection because Google's business model depends on ad tracking.
2. Minimize extensions and plugins
Every installed extension adds a unique parameter to your fingerprint. Use only necessary extensions. Extensions like uBlock Origin also block third-party fingerprinting scripts.
3. Do not over-customize your browser
Custom themes, additional fonts, and unusual display settings make your fingerprint more unique. Browsers with default settings are harder to distinguish from other users.
4. Enable protections in browser settings
In Firefox: about:config > privacy. ResistFingerprinting = true. This setting makes the browser report more generic information, reducing fingerprint uniqueness. In Brave: Shields > Fingerprinting blocking > Strict.
5. Consider common screen resolutions
If you use a very unusual screen resolution (ultrawide, 4K on a small laptop), your fingerprint is easier to distinguish. Using common resolutions helps, but this is not a practical step for everyone.
6. Use private browsing for sensitive activities
Private browsing mode does not fully prevent fingerprinting, but it limits the information available to tracking scripts because there is no stored history or cookies.
7. Check your fingerprint uniqueness
Visit coveryourtracks.eff.org or amiunique.org to see how unique your browser fingerprint is. These sites show what parameters are collected and how different you are from other users. Use this as a basis for deciding what steps to take.
Trade-off: privacy vs convenience
Reducing fingerprint means sacrificing some website convenience:
- Blocking Canvas/WebGL can break visual features on some sites
- Randomizing timezone can cause calendar app issues
- Hiding resolution can affect page layouts Find the balance that suits your needs. For everyday use, browsers with built-in protections (Firefox, Brave) provide adequate protection without sacrificing functionality.
Frequently asked questions
Does a VPN prevent browser fingerprinting?
No. A VPN hides your IP address, but does not change browser parameters like screen resolution, fonts, or canvas fingerprint. VPN and anti-fingerprinting complement each other.
Does incognito mode prevent fingerprinting?
Partially. Incognito mode deletes cookies and history after the session ends, but fingerprint parameters like screen resolution and fonts remain the same. Websites can still recognize your browser during active sessions.
Is browser fingerprinting illegal?
In some jurisdictions, collecting fingerprints without user consent may violate privacy regulations like GDPR. But enforcement against this practice remains limited.
Sources and further reading
- EFF: Cover Your Tracks
- AmIUnique: Browser Fingerprint Research
- Mozilla Wiki: Anti-Fingerprinting in Firefox
Editorial note: Fingerprinting technology continues to evolve. Effective protections today may be less adequate in the future. Monitor developments from sources like EFF for the latest information.
