Canvas Fingerprinting

Canvas fingerprinting is a browser tracking technique that uses the HTML5 <canvas> element to generate a unique identifier based on how a user’s device renders graphics. When a website instructs the browser to draw hidden images or text on the canvas, subtle differences in rendering—due to hardware, software, graphics drivers, fonts, and browser settings—create a distinct “fingerprint.” This fingerprint can be used to identify and track users across websites without relying on cookies.

Also known as: HTML5 Canvas Fingerprinting, Canvas-based tracking

Comparisons

• Canvas Fingerprinting vs. WebGL Fingerprinting: Canvas fingerprinting uses 2D graphics rendering, while WebGL fingerprinting exploits 3D graphics hardware details.
• Canvas Fingerprinting vs. Cookies: Unlike cookies, which store data on the user’s device, canvas fingerprinting collects passive data without explicit user storage, making it harder to detect and block.

Pros

• Bypasses cookie blocks: Effective for identifying users who block or clear cookies.
• No extra permissions: Does not require any special permissions or plugins.
• Security boost: Helps websites enhance security by detecting fraud or suspicious behavior.

Cons

• Privacy invasion: Raises significant privacy concerns due to covert tracking.
• Tough to stop: Difficult for users to prevent without disabling or restricting canvas functionality.
• Enhanced tracking: Can be combined with other fingerprinting methods to increase tracking accuracy.

Example

A news website uses canvas fingerprinting to generate a unique identifier for visitors by drawing invisible text on the canvas and analyzing the pixel data output. This identifier helps the site recognize returning users even when they delete cookies or use private browsing modes, allowing personalized content and targeted advertising.