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User Agent Parser

Parse any browser user agent string to reveal the browser, OS, rendering engine, device type, and bot detection results.

Enter User Agent

Interactive Examples

Click any preset User Agent string below to load and analyze its digital footprint instantly.

Parser Results

Local Real-time Parsing
Browser N/A
Operating System N/A
Device Type N/A
Rendering Engine N/A
CPU Architecture N/A
Bot Detection N/A
Raw User Agent String
N/A
Knowledge Hub

Deep Dive: User Agent Parsing & Compatibility Testing

Understanding User Agent Strings

A User Agent is a string of text that your web browser sends to every website you visit. It acts as a declaration of identity, listing the browser name, rendering engine, and operating system.

Web servers use this header to determine if they should serve mobile-optimized layouts, warn about unsupported versions, or apply specific styling workarounds for rendering engine quirks.

Browser Compatibility Testing

Developers use User Agent spoofing (changing the User Agent string) to test how a website behaves on different devices. For example, testing how an application behaves when hit by a mobile Safari client or a Googlebot indexer.

By parsing these strings, developers can run telemetry and build compatibility matrices to track which versions of engines (like WebKit or Blink) are accessing the system, ensuring layouts stack properly.

The Shift to User Agent Client Hints

Because traditional User Agent strings are long, messy, and contain enough details to passively track users (fingerprinting), modern browsers are adopting User Agent Client Hints (UA-CH).

UA-CH allows browsers to expose details in a clean, key-value HTTP header format. High-entropy information (like full version numbers or CPU build architecture) is only shared if explicitly requested by the server, boosting privacy.

Education

Decoding User Agent Strings and Bot Signals

01

What a User Agent String Contains

A user agent string is a line of text every browser sends with each web request, identifying the browser name and version, rendering engine, operating system, and sometimes CPU architecture and device type. A typical desktop Chrome string looks like Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36, which this parser breaks down field by field.

02

Why Chrome and Edge Both Mention Safari

Modern browsers keep older engine names like Mozilla, WebKit, and Safari inside their user agent string for backward compatibility, so websites that only check for those legacy tokens still serve the correct content. Chrome and Edge are both built on the Blink engine, itself a fork of WebKit, which is why their strings mention Safari even though neither browser is Safari itself.

03

How Bot Detection Works Here

This parser checks the submitted string against known signatures used by search engine crawlers such as Googlebot and Bingbot, social media link previewers, and automated scripts like curl or wget, flagging a match along with the detected bot name and category. Pasting a string like Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) immediately flags it as a search engine crawler rather than a real browser session.

04

Why User Agent Client Hints Are Emerging

Because a full user agent string can be detailed enough to help fingerprint a specific device, browsers are shifting toward User Agent Client Hints (UA-CH), which expose the same browser, OS, and device category information through separate structured headers that a server must explicitly request. Use the Browser Info tool alongside this parser to compare the live values a browser reports against a pasted or historical user agent string.

Good to know

Questions, answered

Quick answers about how this tool works.

A User Agent string is a header sent by your browser to web servers. It identifies the browser name, version, rendering engine, operating system, and hardware architecture, allowing servers to customize or optimize the response for your device.

No. The User Agent Parser runs entirely inside your browser via local JavaScript. Your strings are never stored, logged, or uploaded to any remote API, ensuring absolute privacy.

Historically, early browsers (like Netscape/Mozilla and Safari) had features that web servers checked for. To avoid being blocked by servers that only recognized Netscape or Safari, newer browsers added those names to their User Agent strings to maintain backward compatibility. This is known as User Agent spoofing.

The parser checks the User Agent against a curated list of keywords and patterns used by search engines (like Googlebot, Bingbot, Baidu), social networks (Facebot, Twitterbot), and automated scripts (curl, wget, python). If a pattern matches, the parser flags the request as a bot/crawler.

User Agent Client Hints are a modern alternative to the traditional User Agent string. They provide the same information (browser, OS, device) but in a more structured, secure, and privacy-conscious manner, reducing the risk of passive browser fingerprinting.

Guides

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Plain-language explainers that sit next to this tool.

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