User Agent Parser: Detect Browser & OS
Parse any User-Agent string to extract browser, OS, device, and engine — with a free online tool.
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Tags: user agent parser, browser detection tool, UA string parser
User Agent Parser: Detect Browser & OS A User-Agent (UA) string is the HTTP header browsers send with every request to identify themselves. Parsing it manually is error-prone — a free online parser extracts browser, OS, device type, and engine in one click with no code required. This guide covers the structure of UA strings, what each component means, how parsing works under the hood, and when UA-based detection is (and isn't) the right tool. --- All the tools discussed here are available for free at theproductguy.in — client-side, no sign-up required. Part of the HTTP Debugging Tools Guide — a complete toolkit for diagnosing web requests. --- What Is a User-Agent String? Every HTTP client — browser, bot, mobile app, cURL — includes a header in its requests: That single line encodes five…
Frequently Asked Questions
What is a User-Agent string?
A User-Agent string is an HTTP request header that identifies the software making the request — typically a browser, bot, or HTTP client. It encodes the browser name and version, operating system, and rendering engine in a single (sometimes cryptic) text string.
How do I parse a User-Agent string?
You can paste any UA string into an online User-Agent parser tool to instantly extract structured fields: browser name, browser version, OS name, OS version, device type, and rendering engine. Programmatically, libraries like ua-parser-js (JavaScript) or user-agents (Python) parse UA strings into structured objects.
What browser and OS information does a UA contain?
A typical UA string encodes: the browser family (Chrome, Firefox, Safari, Edge), browser version, operating system (Windows, macOS, Android, iOS), OS version, device type (desktop, mobile, tablet), and the rendering engine (Blink, Gecko, WebKit). The exact fields depend on the browser and its version.
How do websites use User-Agent for device detection?
Servers read the User-Agent header to serve different HTML, CSS, or redirects to mobile vs. desktop clients. CDNs use UA data to vary cached responses. Analytics platforms use it to segment traffic by browser and device. However, UA-based detection is fragile — the modern alternative is CSS media queries or the User-Agent Client Hints API.
What is User-Agent sniffing?
User-Agent sniffing is the practice of reading the UA string in server-side or client-side code to conditionally change behavior based on detected browser or device. It is widely considered an anti-pattern because UA strings are easily spoofed, inconsistently formatted, and increasingly frozen by privacy-focused browsers. Feature detection is the recommended alternative.
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