User Agent Parser
Identify your browser, OS, device, and engine
About User Agent Strings
A user agent string is a line of text that your browser sends to every website you visit. It acts as an identifier, telling the server what browser, operating system, and device you are using. Websites use this information to deliver optimized content and track visitor analytics.
How Browsers Identify Themselves
Every HTTP request includes a User-Agent header. Modern browsers include a complex string that often contains references to multiple browsers and engines for historical compatibility reasons. For example, Chrome's user agent includes "Mozilla", "AppleWebKit", "Chrome", and "Safari" even though it is only Chrome.
What Information Is Included
Name and version of the web browser
Rendering engine like Blink, Gecko, or WebKit
Operating system name and version
Device type, vendor, and model when available
Why It Matters
- Websites serve different layouts for mobile vs desktop browsers
- Analytics platforms use user agents to track browser and OS market share
- Developers test compatibility by checking user agent details
- Bot detection systems identify crawlers via their user agent strings
- Content delivery networks optimize assets based on client capabilities
Related tools: Check your IP address to see what servers know about your connection, view your HTTP headers for the full request your browser sends, or check your location.
Frequently Asked Questions
What is a user agent string?
A user agent string is a text identifier that your browser sends to every website you visit. It contains information about your browser name and version, operating system, device type, and rendering engine.
Why do websites check user agent strings?
Websites use user agents to deliver optimized content for different browsers and devices, serve mobile vs desktop layouts, track browser usage statistics, and sometimes block outdated or incompatible browsers.
Can I change my user agent?
Yes. Most browsers allow user agent modification through developer tools, browser extensions, or settings. This is commonly used for testing how websites appear to different browsers, accessing mobile-only content, or for privacy reasons.
What information does my user agent reveal about me?
Your user agent typically reveals your browser name and version, operating system and version, device type (mobile, tablet, desktop), rendering engine, and sometimes installed plugins. Combined with other data, this contributes to browser fingerprinting.
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