User-Agent Parser

A User-Agent (UA) string is a line of text that a browser or other HTTP client sends in its request headers to identify itself. It typically reveals the browser name and version, the rendering engine, the operating system, and often the device type. For example, "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36" describes Chrome 126 on Windows 10/11.

This is a historical quirk from the 1990s. Early browsers (IE and others) copied the Mozilla prefix so servers would serve them the standard web instead of treating them as unknown clients. Modern browsers keep the prefix for backwards compatibility. Because of this legacy, it is important to parse the whole string rather than assume "Mozilla" means the browser is Firefox.

Chrome is built on the WebKit-derived Blink engine, so its UA string includes both "AppleWebKit/537.36 (KHTML, like Gecko)" (the legacy WebKit signature) and "Safari/537.36" (a fixed compatibility token). Parsers therefore must check for "Chrome/" before "Safari/" — this is exactly what this tool does, and why Edge, Opera, Samsung Internet, and Brave all appear to be Chrome.

Search engines and crawlers identify themselves with distinctive names — Googlebot, Bingbot, Applebot, DuckDuckBot, YandexBot, and many others. Generic fetchers like curl and Wget are also recognizable. This tool flags any agent whose string contains a known bot name or generic bot/crawler/spider keywords, and shows the specific bot name so you can write accurate access rules or analytics filters.

The UA string includes an OS token like "Windows NT 10.0", "Mac OS X 10_15_7", "Android 14", or "iPhone OS 17_4". This lets websites adjust feature availability, download links, or layout. You can disable or spoof this in most browsers, but be aware that doing so may break sites that rely on OS detection for correct downloads or media support.

"like Gecko" is another legacy compatibility token. Firefox uses the Gecko engine, and early WebKit-based browsers added "like Gecko" so Firefox-only content would still be served to them. Today almost every browser includes it, so it carries no real meaning for detection — parsing relies on the real engine tokens such as "AppleWebKit/", "Gecko/", or "Chrome/" (Blink).

User-Agents are a good signal but not infallible. They can be spoofed, disabled, or rewritten by proxies and VPNs. For critical decisions (payments, security checks) you should combine the UA with other signals like IP address, headers, and JavaScript fingerprinting. For analytics and content negotiation, however, parsing the UA — as this tool does — is fast and standard practice.

Yes — completely free, no registration, and 100% private. Parsing runs locally in your browser; the User-Agent string you paste is never sent to any server, stored, or logged. The tool works offline after the page loads.