Browser fingerprinting is a technique websites use to identify a browser (and often a user) by combining signals such as TLS parameters, HTTP/2 settings, header order, canvas rendering, WebGL, fonts, and screen size. Unlike cookies, these signals can persist across sessions and are widely used in anti-bot and fraud systems.
Scrapers that only rotate User-Agent strings are often blocked because the underlying TLS and HTTP/2 fingerprint still reveals automation or non-browser clients. Reference libraries include FingerprintJS and CreepJS.
Try the Browser Fingerprint Report, Headless Signals Checker, and Fingerprinting Resources on the Piloterr toolbox.