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User Agent Checker

Every time your browser requests a web page, it sends a "user agent" string — a line of text that identifies your browser, operating system, and device type. This tool shows your current user agent and can parse any user agent you paste to identify the browser, OS, version, device type, and rendering engine. Useful for web developers debugging compatibility issues, testing responsive designs, or understanding analytics data.

What the User Agent Tells Websites

Browser name and version — Chrome, Firefox, Safari, Edge, etc. Operating system — Windows, macOS, Linux, Android, iOS, ChromeOS. Rendering engine — Blink (Chrome/Edge/Opera), WebKit (Safari), Gecko (Firefox). Device type — Desktop, mobile, tablet, or bot/crawler. Device model — Sometimes specific devices like "iPhone" or "Pixel 8" are identified. This info helps websites serve appropriate content (mobile layout for phones, desktop layout for computers) and log analytics data about visitor devices.

Frequently Asked Questions

Why does every user agent start with Mozilla?+
Historical accident. In the 1990s, Netscape (codename Mozilla) was the dominant browser. Websites started checking for "Mozilla" to serve modern content. When Internet Explorer launched, it faked a Mozilla prefix to get that same content — and every browser since has kept the legacy prefix for compatibility.
Can I change my user agent?+
Yes. All major browsers allow user agent spoofing through developer tools or extensions. This is useful for testing how your website appears to different browsers and devices without actually switching.
Why is user agent detection unreliable?+
User agents can be easily spoofed, many browsers lie about their identity for compatibility, and the strings are inconsistent between browsers. Modern best practice is feature detection (check if a browser supports specific APIs) rather than user agent sniffing.

Built by Derek Giordano · Part of Ultimate Design Tools

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