User Agent Parser

A User Agent Parser is a free tool that reads a browser's User-Agent string and breaks it into the parts that matter: the browser name and version, the rendering engine, the operating system and its version, the device type (desktop, mobile, tablet, or bot), and the CPU architecture. It also flags when a User-Agent belongs to a known crawler like Googlebot or bingbot. Everything runs locally in your browser with a regex-based parser, so no data is ever sent to a server.

What is a User-Agent string?

A User-Agent (UA) is a text header your browser or app sends with every HTTP request to identify itself. A typical UA 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. Packed into that one line are hints about the platform, the layout engine, and the client software. The problem is that the format is messy and full of legacy tokens for compatibility, which is exactly why a parser is useful.

How to use the User Agent Parser

1. Click Use my current UA to load your own browser's navigator.userAgent, or paste any User-Agent string into the box.
2. The results table updates instantly as you type or paste — no button press required.
3. Read the breakdown: browser, version, rendering engine, operating system, OS version, device type, and CPU architecture.
4. Watch for the bot banner, which appears when the string matches a known crawler or automated agent.
5. Click Copy results to grab the full parsed breakdown as plain text.

What each field means

• Browser & version: the client software, such as Google Chrome, Firefox, Safari, Microsoft Edge, Opera, or Internet Explorer, plus its version number.
• Rendering engine: the layout engine that draws the page — Blink (Chrome, Edge, Opera), WebKit (Safari), Gecko (Firefox), or Trident (old IE).
• Operating system & version: the platform, like Windows 10/11, macOS, Android, iOS, iPadOS, Chrome OS, or Linux.
• Device type: desktop, mobile, tablet, smart TV, game console, or bot, inferred from platform and mobile tokens.
• CPU architecture: x86-64, ARM64, ARM, or 32-bit x86 where the UA reveals it.
• Bot flag: whether the string matches a search or AI crawler such as Googlebot, bingbot, GPTBot, or ClaudeBot.

Why parse a User-Agent in the browser?

Server logs, analytics tools, and bot filters all lean on User-Agent parsing, but you often just need to decode a single string quickly and privately. Because this tool is fully client-side, nothing you paste leaves your device — a good fit when the UA came from a sensitive access log. It sits naturally alongside other request-inspection utilities: use a URL Parser to pull apart the request URL that accompanied the UA, then an IP Lookup to see the network and geolocation behind the visitor that sent it.

How the parser detects bots

Real browsers almost always start with Mozilla/5.0 and include an engine token, while crawlers usually name themselves — Googlebot/2.1, bingbot/2.0, or newer AI crawlers like GPTBot and PerplexityBot. The parser checks the string against a curated list of known bots first, then falls back to generic signals such as bot, crawler, spider, and scraper. When a match is found, a banner flags the string so you can treat that traffic differently. To go further, an DNS Lookup lets you verify a claimed crawler by resolving its hostname, since UA strings alone are trivial to spoof.

User Agent Parser features

• Prefills with your own navigator.userAgent and a one-click "use my current UA" button.
• Covers Chrome, Edge, Firefox, Safari, Opera, Internet Explorer, Samsung Internet, and common mobile browsers.
• Recognizes major search and AI crawlers, including Googlebot, bingbot, GPTBot, ClaudeBot, and Bytespider.
• Clean results table with a copy button and a clear bot/crawler flag.
• 100% client-side — no external libraries, no server calls, nothing stored.

Parsing a UA is one piece of investigating web traffic. When you need to know who owns the domain or IP behind a request, a WHOIS Lookup reveals registration and ownership details. Remember that User-Agent strings are self-reported and easy to forge, so treat the parsed result as a strong hint rather than proof of identity.

Frequently Asked Questions

What is a User-Agent string used for?

Websites and servers use the User-Agent to identify the browser, operating system, and device making a request. This drives feature detection, responsive layouts, analytics, and bot filtering. It is sent automatically in the HTTP header of every request your browser makes.

Can I trust the parsed browser and OS results?

Treat them as strong hints, not proof. User-Agent strings are self-reported and can be changed or spoofed by anyone, so a string claiming to be Googlebot might not be. For anything security-sensitive, verify with a reverse DNS lookup or IP checks rather than trusting the UA alone.

How does the tool detect bots and crawlers?

It matches the string against a curated list of known crawlers such as Googlebot, bingbot, DuckDuckBot, GPTBot, and ClaudeBot, then falls back to generic keywords like bot, crawler, spider, and scraper. When a match is found, the tool flags the string and names the detected bot.

Does this tool send my User-Agent anywhere?

No. All parsing happens entirely in your browser with JavaScript regular expressions. Nothing you paste — including your own User-Agent — is transmitted to any server or stored anywhere.

Why do all browsers include the word "Mozilla" in their UA?

It is a historical quirk. Early browsers claimed to be Mozilla-compatible to receive rich content, and the token stuck for backward compatibility. Today nearly every mainstream browser still begins its User-Agent with Mozilla/5.0, which is why the parser relies on engine and browser tokens instead.

What is the difference between a browser and a rendering engine?

The browser is the application you use (Chrome, Firefox, Safari), while the rendering engine is the component that turns HTML and CSS into pixels. Chrome, Edge, and Opera all use the Blink engine, Safari uses WebKit, and Firefox uses Gecko, so different browsers can share the same engine.