| User-Agent | Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; [email protected]) |
|---|---|
| Accept-Language | unknown |
JavaScript is required to show your browser fingerprint.
This data is what any website can read from your browser. It is shown here only in your browser and is not stored.
Your user agent is a short string your browser sends with every request, nominally describing itself and the platform it runs on. Combined with everything else a page can read — screen size, language, time zone, installed fonts — it forms a surprisingly specific description of your device.
Below is your own user agent string and what a website can determine from it.
Nearly every browser in the world sends a string starting with Mozilla/5.0, including browsers with no connection to Mozilla whatsoever. It is a historical accident that never got cleaned up.
In the 1990s some servers checked the user agent before sending modern HTML, so competing browsers began claiming to be Netscape to avoid being served a degraded page. Every browser since has inherited the pretence, adding its own identifier further along the string. The result is a format that is almost impossible to parse reliably — which is precisely why it is being frozen and reduced.
The user agent alone is not very identifying; millions of people share the same one. The concern is combination. Add screen resolution, colour depth, time zone, language, platform, available fonts and how your graphics hardware renders a test image, and the set of people matching all of those at once can collapse to a handful — or to you alone.
This is what makes fingerprinting awkward to defend against: it requires no cookies and no storage, so clearing your browser data does not reset it. Each individual value looks harmless, and the identifying power comes entirely from having many of them together.
Counter-intuitively, an unusual configuration can make you easier to track. A browser reporting a fake user agent that contradicts its other properties stands out far more than one blending into a large crowd.
The approaches that genuinely help are the ones that make many users look identical: Tor Browser, which deliberately makes every instance report the same values, or Firefox's resist-fingerprinting mode. Beyond that, content blockers reduce how many third parties get to run the measurement at all — often the more practical everyday improvement.
It is a string your browser sends with every request, describing the browser, its version and the operating system. Servers use it to adapt responses, and analytics tools use it to report which browsers visitors use.
For historical compatibility. In the 1990s servers checked for Netscape before serving modern pages, so other browsers started claiming to be it. Every major browser has carried the prefix ever since, regardless of its actual engine.
Yes, through developer tools or an extension. It is useful for testing, but as a privacy measure it often backfires: a user agent that contradicts your browser's other detectable properties makes you more distinctive, not less.
It is identifying a visitor by combining many device characteristics — user agent, screen size, time zone, language, fonts, graphics rendering — into a signature. It needs no cookies, so clearing browser data does not reset it.
Use a browser designed to make all users look alike, such as Tor Browser or Firefox with resist-fingerprinting enabled. Content blockers also help by reducing how many third parties can run the measurements at all.