User Agent Parser

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How to Use User Agent Parser

Your current user agent is automatically detected and parsed on load — see your browser, OS, device type and engine. Paste any other user agent string (from server logs, analytics, or a colleague\u0027s screenshot) to parse that instead. The detection uses pattern matching for the most common browsers and operating systems.

About User Agent Parser

Every time your browser requests a web page, it sends a User-Agent header — a string of text that identifies itself to the server. It usually looks something like Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36 — and that one line contains enough information to identify your browser (Chrome), its version (126), your operating system (Windows 10/11), and the rendering engine (Blink, via AppleWebKit). The user agent string is one of the oldest pieces of the web, dating back to the first browser war in the 1990s, and its history explains why every modern browser still claims to be "Mozilla/5.0" — a compatibility artefact from a time when servers served different content to different browsers and everyone wanted to be treated as Netscape-compatible.\n\nDevelopers, system administrators, and security analysts encounter user agent strings in several contexts: parsing server access logs to understand what browsers visitors are using, debugging a website that behaves differently in different browsers ("this bug only happens in Safari, what version is the reporter on?"), analysing bot traffic (many crawlers and scrapers announce themselves via distinctive user agents), or converting a raw log line back into human-readable browser/OS names. This tool automates that parsing: paste any user agent string and the recognised components are extracted and displayed in a clear, structured grid.\n\nThe parsing is done entirely in your browser using pattern-matching regular expressions — no server request, no external API. The regex rules cover the most common user agent patterns: Chrome/Chromium on all platforms, Safari on macOS/iOS, Firefox on all platforms, Edge (Chromium-based), Opera, and the major operating systems (Windows, macOS, Linux, Android, iOS). The tool also detects the device type (Desktop, Mobile, or Tablet) and the rendering engine (Blink for Chrome/Edge/Opera, WebKit for Safari, Gecko for Firefox).\n\nLimitations to be aware of: user agent parsing is inherently heuristic. There is no single authoritative registry of user agent formats — each browser uses its own convention, and many less common browsers (Samsung Internet, UC Browser, Brave without its distinctive UA token) deliberately mimic Chrome\u0027s signature to avoid compatibility problems. A user agent that simply says "Mozilla/5.0 ... Chrome/126" could be Chrome, Brave, Vivaldi, Samsung Internet, or any Chromium-based browser — the string alone does not always distinguish them. This tool reports what the user agent claims to be, which for the most common browsers is usually accurate.\n\nFor precision analytics (exact browser, version, features), user agent strings have been superseded by client-side feature detection and the User-Agent Client Hints API, but user agent logs remain ubiquitous in server logs, CDN dashboards, and SEO tools — and are still the first thing you see when debugging a browser-specific issue from a user report. This tool turns that wall of text into something readable in one click.

Details & Tips

Parsing logic: the tool starts with the user agent string you provide (or auto-detects from navigator.userAgent). It applies a sequence of regex patterns, ordered from most specific to least specific, because simpler patterns can false-match on more specific strings (e.g., both "Chrome" and "AppleWebKit" appear in Edge user agents — checking for Edge first prevents misidentification as Chrome). OS detection looks for explicit platform tokens (Windows NT, Mac OS X, Android, iPhone/iPad). Browser detection uses the browser\u0027s own identifier token: Edg/ for Edge, OPR/ for Opera, Firefox/ for Firefox, Safari/ but only when Chrome is absent (Safari happens to also contain "Safari" in Chrome\u0027s UA, but Chrome also says "Chrome/", so we check Chrome first), and Chrome/ for everything else Chromium-based. Device detection uses Mobile/Tablet keywords and iOS device indicators. When a detected value is "Unknown", it means the heuristic did not match — not that the value does not exist, just that the parser could not extract it. Copy the user agent string from your server logs, analytics tools, or error reports to identify the exact browser/OS combination a visitor was using.

Frequently Asked Questions

What is a user agent string?

It is a text header that your browser sends to every website you visit, identifying itself by name, version, and operating system. Every server log, analytics tool, and CDN records it. Parsing it reveals the browser, OS, and device type the visitor was using.

Why does my browser still say "Mozilla/5.0" even though I am not using Mozilla?

Historical compatibility. In the 1990s, servers checked for "Mozilla" to serve advanced features to Netscape users. When Internet Explorer, then Chrome, then every other browser appeared, they all included "Mozilla" in their user agent to ensure they received the same content. This artefact has persisted for decades and every modern browser still starts with Mozilla/5.0.

Can user agent parsing identify every browser accurately?

Not perfectly. Many Chromium-based browsers (Brave, Vivaldi, Samsung Internet) use Chrome\u0027s user agent signature for compatibility and do not always include their own distinguishing token. The parser reports what the user agent claims to be — for Chrome, Edge, Firefox, Safari, and Opera this is accurate. For lesser-known Chromium browsers, it may report "Chrome" when the user was actually using Brave or Vivaldi.

Does this tool send my user agent to a server?

No. Parsing runs entirely in your browser using JavaScript regex matching — nothing is transmitted. If you enter a custom user agent string, that is also parsed locally and never leaves your device.

Why would I need to parse a user agent string?

Common scenarios: (1) debugging a browser-specific bug from a support ticket that includes a user agent, (2) understanding what browsers your visitors use from server access logs, (3) identifying bot/crawler traffic patterns, (4) checking what information your own browser reveals about itself.

How do I find my own user agent string?

This tool auto-detects it on page load. You can also type "what is my user agent" into Google — many sites will display it. In Chrome DevTools (F12), go to Console and type navigator.userAgent. The tool's "Detect my browser" button refills the textarea with your current user agent at any time.

What does "Unknown" mean in the results?

The heuristic pattern matching could not identify that component. This happens with uncommon or very old browsers, custom user agents (some bots, scrapers, or command-line tools), or user agents that have been deliberately modified. "Unknown" is the parser saying "I do not recognise this", not "this value does not exist".

What is a rendering engine?

The rendering engine is the core component that parses HTML/CSS and draws the page. Blink (used by Chrome, Edge, Opera, and most Chromium browsers) is the most common. WebKit (used by Safari) is its ancestor. Gecko (used by Firefox) is the other major independently developed engine. The engine determines which CSS features are supported and how pages render.

Can I copy the detection result or just view it?

Results are displayed in a grid — select and copy any field value. All text is selectable. A "copy all as JSON" feature is not provided because most users need one or two specific fields (browser + version, usually).

Will this tool work with user agents from server logs that are years old?

Yes — a user agent string is just text, and the parsing logic matches patterns, not dates. An Internet Explorer 6 user agent from 2005 will parse correctly (browser = IE, version = 6, OS = Windows XP) because the parser includes patterns for older browsers.