Fingerprinting

Recognition without storage

Fingerprinting identifies your browser from its characteristics rather than from anything stored on your device. Clearing cookies does not help, because nothing was ever saved. The identifier is you — or rather, the particular combination of settings your browser reveals.

Individually these details are unremarkable. Combined, they are often unique: time zone, language, screen dimensions, installed fonts, GPU model, audio stack behaviour, and dozens more.

How the common techniques work

Canvas

The page draws text or shapes to an invisible canvas and reads the pixels back. Tiny differences in GPU, driver, and font rendering make the output subtly different between machines — and stable on the same one.

WebGL

Similar idea with 3D rendering, plus the graphics card and driver strings, which are highly distinguishing on their own.

AudioContext

The browser processes an audio signal that is never played. Floating-point differences across audio stacks produce a stable value.

Fonts

By measuring rendered text dimensions, a page can infer which fonts you have installed — which often reflects your OS, region, and installed software.

Why blocking all of it breaks the web

Every one of these APIs has an ordinary purpose. Canvas draws charts. WebGL runs maps and games. AudioContext powers audio tools. Font measurement lays out text. Blocking them outright breaks a great deal of the web.

Worse, aggressive anti-fingerprinting can increase how identifiable you are. A browser that reports implausible values stands out from the crowd. Blending in often beats hiding.

This is why Sessyn reports fingerprinting-related behaviour honestly — distinguishing exposed, requested, allowed, blocked, and possible — instead of claiming that using an API is proof of intent.

Last reviewed: 2026-09-12