What Is My User Agent
See the exact user agent string your browser is sending, with the browser, version, engine and operating system parsed out for you.
What a user agent is
Every time your browser asks a server for a page, it introduces itself with a user agent (UA) string - a compact line naming the browser, its version, the rendering engine and your operating system. It exists so servers can, in principle, tailor a response: send a lighter page to an old browser, or a mobile layout to a phone. Everything above is read live from your browser, entirely on this page. Nothing is uploaded.
Why the string is such a mess
UA strings are a museum of browser history. For compatibility, nearly every browser still starts its UA with Mozilla/5.0, and Chromium-based browsers also claim to be Safari and AppleWebKit. That is why a parser has to check tokens in a careful order: Edge (Edg) and Opera (OPR) both contain the Chrome token, so they must be tested first, and Chrome must be tested before Safari because Chrome's UA contains the word Safari too. Get the order wrong and every Chromium browser looks like plain Chrome or Safari.
The user agent is being reduced
Because the UA exposed so much detail, it became a tracking tool - sites combined it with other signals to fingerprint visitors. Browsers are now freezing and trimming it, rounding the version and OS down to vague values and moving precise data to a newer, permission-based system called User-Agent Client Hints. A practical upshot: never trust the UA for anything that matters, because it is self-reported and easily spoofed from developer tools. If you are inspecting what your connection exposes, pair this with the what is my IP tool, or decode a token with the JWT decoder.