What Is My User Agent
Your browser's user agent string and what it reveals.
Your browser, identified
The page shows your full user agent string with one-click copy, the browser and operating system it parses to, and the facts the browser reports about itself: languages, CPU threads, touch points, cookie state. All read locally from the browser's own APIs โ nothing is looked up or transmitted.
The everyday use is support: when an IT desk or developer asks "what browser are you on?", copying the string here answers precisely, including the version numbers that matter for reproducing bugs.
Why every browser claims to be Mozilla
Read the string and you'll find Mozilla, AppleWebKit, KHTML and Safari all mentioned by a browser that is none of them. This is thirty years of compatibility theatre: 1990s sites served features by sniffing the string, so each new browser impersonated its predecessors to avoid the broken version, and the lies fossilised into every string sent today.
The string is also losing detail on purpose: browsers now freeze parts of it to blunt fingerprinting, so the OS version shown may be deliberately pinned to an old value. For code the lesson is settled โ detect features, not strings. Your screen's numbers live in the resolution checker, and the wider question of what your device leaks is the metadata guide's territory.
Frequently asked questions
What is a user agent?
A string your browser sends with every request identifying itself โ browser, version, OS. It is how sites know to serve you mobile layouts or warn about old browsers.
Why does my user agent mention Mozilla when I use Chrome?
Historic compatibility: browsers impersonated each other for decades so sniffing sites wouldn't serve them broken pages. The tokens are fossils every browser still ships.
Can I trust the OS version shown?
Not fully โ browsers deliberately freeze parts of the string to reduce fingerprinting, so newer OS versions may report as an older one.
Does checking this send my data anywhere?
No โ the string is read from your browser locally, on this page, with no lookup service involved.