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User Agent Parser

Decode, analyze, and debug User Agent strings. Identify browsers, OS, bots, and feature capabilities with high-precision regex parsing.

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About

The User Agent (UA) string is a fundamental component of web architecture, acting as a digital handshake between a client and a server. However, due to the Browser Wars of the 1990s and legacy compatibility quirks, these strings have become notoriously convoluted. For example, almost every modern browser claims to be Mozilla/5.0 to bypass ancient server-side sniffing logic.

This tool goes beyond simple string extraction. It utilizes a deep Regex Dictionary to identify not just the browser, but the rendering engine (e.g., Blink, Gecko), the specific operating system version, and device type. Crucially for SEO and DevOps, it distinguishes between legitimate traffic and automated scrapers (bots) by analyzing signature tokens.

user agent browser detection seo tools bot detector parser

Formulas

The parsing logic relies on a priority-based pattern matching algorithm. A simplified representation of the matching set S is:

Parse(ua) =
{
Edge if ua contains Edg/Chrome if ua contains Chrome/ ∧ ¬EdgeSafari if ua contains Safari/ ∧ ¬ChromeUnknown otherwise

We also calculate a Capability Score based on the browser version v against a feature matrix M:

Supports(feature) ⇔ v ≥ Mfeature

Reference Data

User Agent TypeExample StringDetected Environment
Modern Desktop (Windows)Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36Chrome 120 on Windows 10/11
Modern Mobile (iOS)Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1Safari 17 on iPhone (iOS 17)
SEO Crawler (Google)Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.6045.160 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)Googlebot (Smartphone)
Legacy (IE)Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like GeckoInternet Explorer 11 on Windows 7
Script / Botcurl/7.64.1cURL Command Line Tool
Game ConsoleMozilla/5.0 (PlayStation 4 3.11) AppleWebKit/537.73 (KHTML, like Gecko)Sony PlayStation 4

Frequently Asked Questions

This is a historical artifact known as "compatibility spoofing". In the early web, Netscape (Mozilla) was the dominant browser. When Internet Explorer arrived, it had to pretend to be Mozilla to receive advanced content from servers. Later, Chrome had to pretend to be Safari (WebKit) to render pages correctly. Today, a standard Chrome UA string contains tokens for Mozilla, Apple, Gecko, and Safari to ensure maximum compatibility.
Yes, trivially. Any client can send any string it wants in the HTTP headers. While this tool can parse the string, it cannot guarantee the client is telling the truth. However, legitimate bots (like Googlebot) can be verified via reverse DNS lookups (which requires server-side access), but parsing the string is the first step in identification.
Partially. Microsoft decided to freeze the reported version in the User Agent string to "Windows NT 10.0" for both Windows 10 and 11 to prevent compatibility breakage. To definitively distinguish Windows 11, a website must use "Client Hints" (High Entropy Values). Without Client Hints, a pure string parser sees Windows 10 and 11 as identical.
The **Browser** (e.g., Chrome, Edge) is the software application you interact with (UI, bookmarks, history). The **Engine** (e.g., Blink, Gecko) is the underlying code that interprets HTML, CSS, and JavaScript and draws the pixels on the screen. Notably, Chrome and Edge both use the "Blink" engine, meaning they render websites almost identically.