Stop Canvas Fingerprinting

TL;DR

Canvas fingerprinting is hard to completely block, but you can significantly reduce its effectiveness by disabling or sandboxing the canvas element in your browser. Browser extensions and privacy-focused browsers offer additional protection.

What is Canvas Fingerprinting?

Websites use a hidden HTML element called <canvas> to draw images using JavaScript. Each computer renders these images slightly differently due to variations in hardware, drivers, and software. This creates a unique ‘fingerprint’ that can be used to identify you even without cookies.

How to Prevent Canvas Fingerprinting

1. Disable Canvas (Not Recommended for Most Users): This is the most effective method but will break many websites.
   • Firefox: Type about:config in the address bar, accept the risk, search for security.canvas.enabled and set it to false.
   • Chrome/Edge: This is more difficult as there’s no direct setting. You’ll need a browser extension (see step 3).
2. Sandbox the Canvas Element: This limits the information canvas fingerprinting can access.
   • Firefox: Firefox offers built-in sandboxing features. You may need to adjust advanced privacy settings.
   • Chrome/Edge: Extensions are generally required for effective sandboxing (see step 3).
3. Use Browser Extensions: Several extensions aim to mitigate canvas fingerprinting.
   • Privacy Badger: Automatically learns to block trackers, including those using canvas fingerprinting. Available for Firefox and Chrome.
   • uBlock Origin: A powerful ad blocker that can also block tracking scripts. Requires adding specific filter lists designed to counter canvas fingerprinting (search online for current lists).
   • CanvasBlocker: Specifically designed to prevent canvas fingerprinting by injecting noise into the canvas data. Available for Chrome and Firefox.
4. Use a Privacy-Focused Browser:
   • Brave Browser: Includes built-in protection against fingerprinting, including canvas fingerprinting.
   • Tor Browser: Offers strong anonymity and blocks many tracking techniques by default. However, it can be significantly slower than other browsers.
5. Regularly Clear Your Browser Data:
   • Clear your cache, cookies, and browsing history frequently. This won’t prevent fingerprinting directly but makes it harder to track you over time.
6. Use Multiple Browsers: Using different browsers for different activities can help isolate your fingerprints.
   • For example, use one browser for sensitive tasks (banking) and another for general browsing.

Checking if You’re Fingerprinted

You can use websites like BrowserLeaks Canvas Test to see how unique your browser fingerprint is.

Important Considerations

• No Perfect Solution: Completely blocking canvas fingerprinting is very difficult, as websites can use various techniques to circumvent protections.
• Website Compatibility: Disabling or sandboxing the canvas element may break some website functionality.
• Ongoing Arms Race: Fingerprinting techniques are constantly evolving, so you need to keep your browser and extensions updated.