Browser fingerprint

What a browser fingerprint is

Every time a page loads, the browser hands over a long list of facts: the user agent, screen size and color depth, installed fonts, time zone, languages, hardware concurrency, memory, touch support, audio and graphics capabilities, plus hashes of how it renders a canvas image or WebGL scene. Each fact is common on its own. Combined, the set is often unique among millions of visitors, and it stays the same across sessions. That set is the browser fingerprint.

No cookie is needed and nothing is stored on your machine, so clearing data does not reset it. Fingerprinting works in private windows and across sites that share the same script.

Why it matters

Fingerprints are used for two different purposes. Advertising networks use them to follow people across sites. Fraud and account-security systems use them to decide whether a login looks like the usual device and whether the browser is a real one at all. The second use is what matters for anyone testing a proxy or antidetect setup:

• Automation flags such as navigator.webdriver or headless markers mark the session as a bot immediately; our anonymity score deducts 20 points for them.
• Internal contradictions are the next tier: a mobile user agent with a desktop screen, a time zone that does not fit the IP, languages that do not fit the country, or client hints that disagree with the user agent string.
• A fingerprint that is "too unique" or changes on every load stands out as much as a plain one.

How to check

The browser fingerprint page collects the same signals a tracking script would and shows them grouped, with the derived hashes and any inconsistencies highlighted. Use the canvas fingerprint test for the rendering hash alone, the user agent parser to see how your UA string is read, and HTTP headers for the server-side view.

How to reduce it

Browsers with built-in protection make common values more common rather than hiding them, which is the sound approach. Antidetect browsers go further by generating a complete, consistent profile. In both cases the goal is to look like a plausible, ordinary device, not an unusual one. Verify a profile after creating it, after a browser update, and after changing the proxy, since the IP-dependent signals move with the proxy.