🔬 UA Detection

What Is My User Agent?

See your complete browser user agent string, parsed into browser, version, OS and engine. Copy your UA instantly.

Advertisement
Your full user agent string
Browser
Version
OS
Engine
Platform
Mobile

What is a user agent?

A user agent string is a text identifier your browser sends with every HTTP request. It tells websites which browser, version, and operating system you're using, so they can serve compatible content.

Example: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0

User agent strings are used for browser detection, analytics, content negotiation, and A/B testing. They can also be spoofed — meaning you can change your UA to appear as a different browser.

Advertisement

Why user agents matter for developers

User agents are sent with every HTTP request. Servers use them for browser detection, device-appropriate content serving, and analytics. Feature detection is now preferred over UA sniffing as UAs can be spoofed and are increasingly reduced for privacy.

User agent reduction

Chrome and other browsers are reducing UA string detail to prevent fingerprinting as part of the Privacy Sandbox initiative. Future UAs will contain less specific OS and version information. The User-Agent Client Hints API is the modern replacement.

What is a user agent? +
A text string sent by your browser with every web request, identifying your browser, version, and OS to the server.
Can I change my user agent? +
Yes. Chrome DevTools (F12 > Network conditions) lets you override your UA. Extensions also allow UA switching for compatibility testing.
Why does my UA say Mozilla? +
All major browsers include Mozilla/5.0 for historical compatibility, dating to the Netscape era when servers checked for Mozilla to serve modern content.
What is UA reduction? +
Browsers are progressively stripping version details from UA strings to prevent fingerprinting. The UA-CH API provides an alternative for legitimate use cases.