Free tool · canvas and WebGL
Canvas fingerprint test
See your canvas, WebGL and audio fingerprints, and whether a site can tell that they were changed.
Checking your browser…
The check runs in your browser and takes about five seconds.
IP location by DB-IP. How this test works.
Direct answer
A canvas fingerprint comes from drawing text and shapes in a hidden canvas and reading the pixels back. Small differences in graphics cards, drivers and fonts make the result differ between computers. Some browsers and tools add noise to hide it, and this test shows whether a site can see that noise.
How canvas, WebGL and audio fingerprints work
Canvas: the page draws text, emoji and shapes, then reads the pixels. Fonts, anti-aliasing and the graphics stack change the result.
WebGL: the page reads the name of the graphics card and its limits, and can draw a 3D scene. The name must fit the operating system: a Windows computer does not have an Apple M2 chip.
Audio: the page renders a short sound without playing it. The numbers differ slightly between devices.
Why added noise can be seen
Noise makes the hash differ from the real one, but a plain colour or a constant sound should read back exactly. When it does not, sites see that something changed the output. Firefox, Brave and Safari add noise as a privacy feature, so sites expect it from them. In Chrome and Edge, noise is unusual.
A stable fingerprint per profile that fits the rest of the identity is less suspicious than noise that changes on every read.
Questions
Can I block canvas fingerprinting?
You can block canvas reads with an extension, but a browser that returns nothing or random pixels stands out. Firefox and Brave protect you by default in a way that sites expect.
Why does my canvas hash change between browsers?
Each browser draws text and shapes in a slightly different way, so the same computer has a different canvas hash in Chrome and in Firefox.