Guide · 4 min read
What is canvas fingerprinting?
Canvas fingerprinting is one of the most common tracking techniques on the web. A site quietly draws text and shapes in your browser, reads back the pixels, and turns them into an ID.
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Scan my browser freeHow it works
A script creates an invisible canvas element, draws text, emoji and gradients on it, then exports the image. Your graphics card, drivers, operating system and installed fonts each render the drawing slightly differently. Hashing the pixels gives a short code that stays the same on every visit.
Why it's so effective
It needs no permission, leaves nothing on your device, and survives clearing cookies. Combined with WebGL (which reveals your GPU model) and other signals, it is a major part of a full browser fingerprint.
Who uses it
Advertising networks, analytics providers, and fraud-prevention services. Studies have found canvas fingerprinting scripts on a large share of popular websites.
How to defend against it
Brave adds random noise to canvas readings per site; Tor Browser asks permission before a site can read canvas data; Firefox's resistFingerprinting blocks it. See our full guide on how to block browser fingerprinting, and check your own canvas hash with the free scanner.