Canvas fingerprint

Canvas is an HTML5 element on which a page can draw text, shapes and gradients. To build a fingerprint, a site's script draws a hidden image, reads back the resulting pixels and computes a hash from them. You see nothing, and it all takes a fraction of a second.

The same drawing comes out slightly differently on different devices. The result depends on the graphics card and its drivers, the operating system, installed fonts, anti-aliasing and the browser version. A difference of a few pixels is invisible to the eye but completely changes the hash.

On its own a canvas fingerprint is not unique: identical laptops with identical software produce similar results. That is why sites combine it with other signals - WebGL, the font list, screen size, language and time zone. Together they form a browser fingerprint that helps recognize a device without cookies.

A proxy has no effect on the canvas fingerprint. The image is drawn inside your browser, while the proxy only relays network traffic and changes the IP that the site sees. If you open the same site from the same browser through different IPs, the canvas fingerprint stays the same.

Antidetect browsers let you manage this parameter. In them each profile has its own fingerprint settings: some programs add small, stable noise to the image, others keep the device's real value. It is important that the value does not change from request to request within one profile, because constant jumps look suspicious in themselves.

Canvas is not the only method of this kind. A WebGL fingerprint, which describes the graphics card and its capabilities, works in a similar way, and so does an audio fingerprint, where a script processes inaudible sound and hashes the result. They all rely on the same idea: the same task on different hardware gives a slightly different result. Some privacy-focused browsers add noise or forbid reading the canvas by default. But that protection is also visible to a site, because it sets the browser apart from most ordinary users. So every setting option has its pros and cons.

Profile settings are usually combined with a proxy: the browser sets canvas, WebGL and fonts, and the proxy sets the IP and country. The AdsPower guide shows how to do this in practice. It is also worth checking that the profile does not reveal your real address through a WebRTC leak.