Privacy Checker

Features

• Fingerprinting surface summary
• Full list of attributes readable without permission
• Local storage inspection for this site
• Do Not Track and Global Privacy Control status
• Practical hardening suggestions

How to use it

1. The check runs automatically when the page loads.
2. Read the table to see what any site can learn about you.
3. Check the suggestions for ways to reduce the surface.
4. Use Clear storage to wipe what this site has stored.

How browser fingerprinting works

Fingerprinting identifies you without cookies by combining attributes that are individually unremarkable but collectively rare. Your screen resolution, timezone, language, installed fonts, GPU model and the precise way your device renders a canvas element each narrow the field. Combine twenty such values and the result is frequently unique among hundreds of millions of browsers, the Electronic Frontier Foundation's Panopticlick research demonstrated this over a decade ago and it has only become more effective since.

The counter-intuitive part is that hardening can make things worse. A browser with an unusual user agent, a rare screen size and privacy extensions installed is more identifiable than a default one, because those choices are themselves distinguishing. This is why the Tor Browser makes every user look identical rather than making each user look random, and why it discourages resizing the window or installing extensions.

Do Not Track is worth understanding for what it is not. It sends a header politely requesting that you not be tracked, and it is entirely voluntary, almost no advertiser honours it, and enabling it adds one more bit to your fingerprint. Global Privacy Control is a newer signal with actual legal weight in California and some other jurisdictions, where it counts as a valid opt-out request under CCPA. If you want meaningful protection, the effective measures are blocking third-party cookies, using a content blocker like uBlock Origin, and preferring a browser that fights fingerprinting by default.