Glossary

Browser fingerprint

The set of details a browser reveals to every site it visits, from screen size and time zone to fonts, graphics card and rendering quirks. Together they can recognize the same device even after cookies are cleared.

Also called: device fingerprint, digital fingerprint, browser fingerprinting.

A site's script reads dozens of values: the user agent, screen resolution, time zone and language, installed fonts, the graphics renderer, and how the device draws a hidden canvas or processes a short audio signal. No single value is unique, but the combination often is, and it doesn't live in cookies, so clearing them changes nothing.

Anti-fraud systems use it in 2 ways. They link visits from the same device across accounts, and they check whether the parts agree with each other. Fingerprint, a company that sells device identification to sites, calls contradictions such as a profile that claims Safari on macOS while its rendering points to Chromium on Windows "the most reliable tell that a browser is lying about itself."

Antidetect browsers give each profile its own fingerprint. The goal isn't the most unusual one: a consistent fingerprint of a common device that stays the same from visit to visit is harder to flag than a randomized one.