Guide
A User Agent Parser decodes the User-Agent HTTP header string — the technical identifier that browsers and apps send with every web request — and presents the information in a readable, structured format. The raw user agent string is deliberately compact and terse; parsing it reveals the browser name, version, rendering engine, operating system, OS version, and device type.
Every web browser, mobile app, bot, and HTTP client sends a User-Agent header with each request, identifying itself to the server. A typical Chrome on Windows user agent looks like:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36
This single string encodes:
The redundant tokens exist for historical reasons — user agents accumulate compatibility strings because early internet servers would reject requests not containing Mozilla or later Safari compatibility claims. The modern format is effectively a legacy artefact interpreted by pattern-matching libraries.
Web development and debugging: When a user reports a rendering or functionality issue, their browser and OS identify compatibility problems. Knowing a user is on Safari 15 on iOS 15 immediately suggests testing for Safari-specific CSS quirks or missing JavaScript APIs.
Analytics and traffic analysis: Web analytics platforms break down traffic by browser, OS, and device type using user agent parsing. Understanding what percentage of users are on mobile vs. desktop, or on Chrome vs. Safari, informs design and feature prioritisation decisions.
Bot and crawler identification: Search engine crawlers (Googlebot, Bingbot), SEO tools (Ahrefs, Semrush), and malicious bots all have distinctive user agents. Server logs can be filtered by user agent to separate human from automated traffic.
Conditional content serving: Server-side user agent detection is used (though less common now due to client-side feature detection) to serve mobile-optimised content, appropriate file formats, or platform-specific download links.
Security analysis: Suspicious or unusual user agent strings — outdated browsers, headless Chromium, known vulnerability scanning tools — can indicate automated attacks or vulnerability probing. The UtilsGo User Agent Parser decodes user agent strings instantly in your browser.
Decode complex user agent strings into human-readable components instantly.
See exactly what information your browser reveals to websites.
Identify browser version issues or compatibility problems quickly.
Everything runs inside your web browser. We never upload your text, files, or personal data to any servers.
No sign-ups, no subscriptions, and no usage limits. Get your results instantly in a single click.