What is my user agent?
See your exact user agent string right now, decoded into browser, engine and OS. Free, instant, and nothing leaves your browser.
Your user agent is a single line of text your browser attaches to every request it makes. It is meant to tell a server which browser, rendering engine and operating system it is talking to, so the server can send back a page that works. Yours is shown in full above, exactly as a web server receives it.
A modern user agent looks like a small archaeological dig. It usually starts with "Mozilla/5.0" for historical reasons that have nothing to do with Mozilla, then lists platform tokens like "Windows NT 10.0" or "Macintosh", then the engine ("AppleWebKit", "Gecko"), and finally the browser and version. Chrome, Edge and Opera all still claim to be "like Gecko" and "Safari" because sites once sniffed for those names.
Because so many products cram compatibility tokens into the string, the user agent is more of a compatibility flag than a clean fact sheet. That is also why it is only a hint, not proof: any client can send any string it likes.
What you should know
Why sites collect it
Servers read the user agent to pick a layout, serve the right download, warn about unsupported browsers, gather rough analytics on which browsers visitors use, and block obvious bots. Advertisers and fingerprinting scripts fold it into a device profile because the exact version numbers narrow down who you are.
Privacy implications
On its own a user agent rarely identifies you, but it is one of the most reused fingerprinting signals because it carries browser, version and OS in one string. Combined with your screen size, timezone and fonts it becomes far more revealing. Browsers have started freezing or trimming the string (Chrome's User-Agent Reduction) precisely to blunt this.
How to change or hide it
You can change your user agent per site with an extension, or globally in a browser's developer tools under the device toolbar. Some privacy browsers (Tor Browser, Brave) deliberately send a common, generic string so you blend in with everyone else. Spoofing it can break sites that branch on it, so test before you rely on it.
Frequently asked questions
Is a user agent unique to me?
Usually not by itself, since millions of people run the same browser version on the same OS. It becomes identifying when combined with other signals like screen size, timezone and installed fonts.
Can I fake my user agent?
Yes. It is just a request header, so an extension or your browser's dev tools can send any value. Sites cannot verify it, though some behaviour checks can catch obvious mismatches.
Why does Chrome's user agent mention Safari and Gecko?
For backward compatibility. Years ago sites checked for those names to enable modern features, so every browser kept the tokens to avoid being served a worse page.