User Agent Parser
Decode any browser User Agent string into browser, OS, device
About the User Agent Parser
Every browser sends a User Agent string with each HTTP request — a compact identifier that describes the browser name, version, rendering engine, operating system, and device type. Web servers use it for logging, developers use it for feature detection, and testers use it to simulate different browsers. Reading the raw string is possible but opaque: a typical Chrome on Windows string runs to over 100 characters and includes multiple version numbers for historical compatibility reasons.
This parser reads your browser's User Agent automatically on page load and breaks it into labelled cards — Browser, Operating System, and Device — so you can see at a glance what your browser is reporting. You can also paste any custom User Agent string to decode it: useful for diagnosing what a web server logged from a mobile client, understanding what a headless browser or scraper is identifying as, or verifying that a custom UA set in testing tools is parsed correctly. All processing happens in the browser using regular expressions — no data is uploaded anywhere.
How to Use the User Agent Parser
- Your current browser's User Agent string loads automatically in the text area at the top of the page.
- Read the three parsed cards below: Browser (name, version, rendering engine), Operating System (name and version), and Device (Desktop, Mobile, or Tablet).
- To decode a different User Agent — for example, one from a server log or a testing tool — paste it into the text area and click "Parse".
- Click "Use My UA" at any time to reset the text area back to your real browser's User Agent string.
Why Use ToolForge’s User Agent Parser
- Detects the correct browser from ambiguous strings: Chrome, Edge, Opera, Firefox, and Safari all include "Safari" and sometimes "Chrome" in their UA strings for historical compatibility. The parser applies the correct detection order — Edge before Chrome, Opera before Chrome — to return the real browser name.
- Covers all major OS variants including the Windows NT version mapping (10.0 → Windows 10/11), macOS dot-version reconstruction from underscored OS X strings, and iOS/iPadOS separation.
- Editable input for custom strings: paste a UA from a log file, a scraper, or a testing harness and get an instant structured breakdown without writing regex yourself.
- Fully offline: the parser uses compiled regular expressions that run in your browser. No API call is made, no UA string is sent to a server.
Frequently Asked Questions
What is a User Agent string?
A User Agent string is a text identifier that browsers include in the HTTP request header `User-Agent:` sent to every website. It tells the server which browser, version, operating system, and device type is making the request. Web servers use this for analytics logging, content negotiation, and legacy device detection.
Why does my Chrome UA say it is also Safari?
For historical compatibility, Chrome, Edge, and most Chromium-based browsers include `Safari/` and `AppleWebKit/` in their UA strings. This allows older server-side detection code written to recognise "Safari" to also work with these browsers. The correct way to detect Chrome is to look for the `Chrome/` token, which is what this parser does.
Can I change or spoof my User Agent?
Yes. Most browsers allow you to override the User Agent string in developer tools (Chrome DevTools → Network Conditions panel, for example). Browser extensions and command-line flags also allow UA spoofing. This tool always reads whatever string the browser is actually sending, making it useful for verifying that a spoofed UA is formatted correctly.
What does the Engine field mean?
The engine is the underlying rendering core: Blink (Chrome, Edge, Opera), Gecko (Firefox), WebKit (Safari), or Trident (Internet Explorer). Engine matters because the same browser feature may behave slightly differently across engines, which is why web developers often test against multiple engines rather than just multiple browser brands.
