Blog | G5 Cyber Security

Browser Fingerprinting: What You Need to Know

G5 Cyber Security

TL;DR

Browser fingerprinting is a sneaky way websites track you without cookies. It uses details about your browser and computer setup to create a unique ‘fingerprint’. While it’s hard to completely avoid, you can reduce its accuracy by using privacy-focused browsers, extensions, and regularly clearing data.

What is Browser Fingerprinting?

Imagine everyone has a slightly different fingerprint. Websites used to rely on cookies to identify you, but many people block those now. Browser fingerprinting is an alternative. It doesn’t install anything; it just reads information your browser already sends.

How Does Browser Fingerprinting Work?

  1. Data Collection: Websites collect lots of seemingly harmless details, including:
    • Your browser version (e.g., Chrome 118)
    • Operating system (e.g., Windows 10)
    • Installed fonts
    • Plugins and extensions
    • Screen resolution
    • Language settings
    • Timezone
    • Hardware details (CPU, GPU)
  2. Hashing: This data is combined and run through a special algorithm called a hash function. The result is a unique ‘fingerprint’ for your browser.
  3. Tracking: Websites store this fingerprint. When you revisit, they compare the new fingerprint to the old one. If it’s similar enough, they know it’s likely you – even without cookies!

Is Browser Fingerprinting Accurate?

It depends. A very common browser setup (e.g., latest Chrome on Windows 10) will have a lot of matches, making it less accurate. A unique setup is much easier to identify.

How Can You Protect Yourself?

  1. Use a Privacy-Focused Browser: Browsers like Brave and Tor are designed to resist fingerprinting.
    • Brave: Blocks trackers by default and includes features to randomise your browser fingerprint.
    • Tor: Routes your traffic through multiple relays, masking your IP address and making fingerprinting harder. It’s slower but very effective.
  2. Browser Extensions: Several extensions aim to reduce fingerprinting:
    • Privacy Badger (EFF): Learns to block trackers automatically.
    • CanvasBlocker: Prevents websites from reading your canvas fingerprint (a common technique).
    • NoScript (Firefox only): Blocks JavaScript, which is often used for fingerprinting. Be aware this can break some website functionality.
  3. Regularly Clear Browser Data: Clearing cookies and cache helps, but it’s less effective against fingerprints.
    • In Chrome, go to Settings > Privacy and security > Clear browsing data. Select ‘All time’ for the time range.
  4. Disable Unnecessary Plugins: The more plugins you have, the easier it is to identify your browser.
  5. Use a VPN: A VPN hides your IP address, which is often part of the fingerprint.
  6. Randomize Your Fingerprint (Advanced): Some browsers and extensions allow you to randomize parts of your fingerprint. This makes it harder to track you consistently but can also cause website compatibility issues.
    • Brave has built-in fingerprinting protection options in its settings.

Testing Your Browser Fingerprint

You can see how unique your browser is using these tools:

These tools will show you the data websites can collect and how many other users share your same fingerprint.

Limitations

Completely preventing browser fingerprinting is very difficult. It’s a constant arms race between trackers and privacy advocates. The goal isn’t necessarily to become invisible, but to make it harder and more expensive for websites to track you uniquely.

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