🕵️ User Agent Parser

What is the User Agent Parser?

The user agent string is a single header value, User-Agent, that a browser includes on every HTTP request. A typical desktop Chrome string 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. It packs several facts into one line: the platform (Windows NT 10.0), the rendering engine (AppleWebKit), and the browser and version (Chrome/124). Servers and analytics tools read this to tailor responses, gather statistics, or block bots.

Parsing a UA reliably is harder than it looks because the format is a tangle of historical compatibility tokens. Almost every browser still begins with Mozilla/5.0 for legacy reasons, Chrome includes the word Safari, and Microsoft Edge includes both Chrome and Safari. That is why a parser must check the most specific tokens first: look for Edg before Chrome, and Chrome before Safari, otherwise everything would be misread as Safari. This tool uses ordered regular expression heuristics that follow that priority.

Because the string is self-reported, it can be spoofed, abbreviated, or frozen. Modern browsers are intentionally reducing UA detail (so-called user agent reduction) and offering structured User-Agent Client Hints instead, which expose the same facts in a cleaner, privacy-aware way. Treat any parsed result as a best-effort guess rather than proof: it is great for debugging and analytics, but never use it alone for security decisions.

When to use it

• Quickly checking your own browser, version, and OS to report a bug or confirm an update installed.
• Debugging why a site behaves differently for one visitor by inspecting the exact UA string from their support ticket.
• Testing how server-side or analytics code classifies different devices by pasting sample UA strings.
• Spotting whether a request likely came from a bot, crawler, or automated client rather than a real browser.

How to use the User Agent Parser

1. Your own user agent is shown automatically when the page loads.
2. To inspect a different string, paste it into the text box (or press "Use my browser" to restore your own).
3. Press Parse, or just edit the box, to read the breakdown.
4. Review the browser, version, operating system, device type, and rendering engine cards.

Formula & method

Worked examples

Common UA tokens and what they indicate

Common mistakes to avoid

• Trusting the user agent as proof of identity. The UA is self-reported and trivially changed in browser dev tools or scripts. Use it for analytics and debugging, never as the sole basis for a security or access decision.
• Matching Safari before Chrome or Edge. Chrome strings contain the word Safari, and Edge strings contain both Chrome and Safari. Test the most specific tokens (Edg, OPR) first, or you will label everything as Safari.
• Reading Windows NT 10.0 as exactly Windows 10. Windows 11 still reports Windows NT 10.0 in the UA, so the string alone cannot tell 10 and 11 apart. This tool shows "10 or 11" to reflect that ambiguity.
• Expecting full detail from reduced user agents. Browsers are freezing and trimming UA strings for privacy. Minor versions and some platform details may be missing, which is why Client Hints exist as a structured alternative.

Glossary

User agent (UA)

The identifier string a browser sends in the User-Agent header to describe its software, version, and platform.

Rendering engine

The component that turns HTML and CSS into pixels, for example Blink (Chrome, Edge), WebKit (Safari), or Gecko (Firefox).

Token

A labelled fragment inside the UA string, such as Chrome/124 or Windows NT 10.0, that a parser matches with a pattern.

Client Hints

A newer, structured alternative to the UA string that lets servers request specific browser facts on demand.

Spoofing

Deliberately sending a fake or altered user agent to disguise the real browser, device, or bot.

Frequently asked questions