// decode browser, engine, OS, device & CPU from any user-agent string
Your browser's user-agent:
Browser
—
Engine
—
Operating System
—
Device
—
Device type
—
CPU architecture
—
What is a user-agent string?
A user-agent string is a line of text every browser sends with each HTTP request, identifying the browser, its version, the rendering engine, and the operating system. Servers use it to serve compatible content, and analytics tools use it to report on visitor browsers and devices.
How to use this tool
Your own browser's UA is shown automatically above
Paste any other UA string to decode it instead
Useful for debugging browser-specific bugs from support tickets or server logs
Everything runs locally — no UA string is sent anywhere
Why user-agent parsing is unreliable by nature
User-agent strings are a historical mess. Browsers have spent two decades pretending to be other browsers for compatibility — Chrome's UA contains "Mozilla," "AppleWebKit," "KHTML," "Gecko," and "Safari," none of which describe Chrome itself. This tool parses the string using pattern matching against known browser/OS signatures, which covers the vast majority of real-world UAs but can misidentify obscure or spoofed ones.
Modern browsers are also actively "freezing" and reducing UA string detail (User-Agent Reduction) for privacy reasons, replacing precise OS versions with generic placeholders. For anything security-sensitive, don't rely on the user-agent string alone — treat it as a hint, not a guarantee.
Frequently Asked Questions
Is my user-agent string sent anywhere?+
No. Parsing happens entirely in your browser using the open-source UAParser.js library, loaded once from a CDN. The UA string you paste (or your own) never leaves your machine.
Why does the device field say nothing for a desktop browser?+
Desktop user-agents typically don't include device model information — that field is mainly populated for mobile phones and tablets, which include their manufacturer and model in the UA string.
Can a website fake its user-agent?+
The website can't, but the visitor's browser or an extension can override the UA string it sends. Browser dev tools also let developers manually override it to test how a site responds to different browsers or devices.