User Agent Parser

What the User Agent Parser does

A User-Agent string is the line a browser sends with every request to describe itself: the browser name and version, the layout engine, the operating system, and sometimes the device and CPU architecture. These strings are notoriously messy — full of legacy tokens like Mozilla/5.0 and like Gecko that exist purely for compatibility. This tool takes any user agent you paste and uses the well-known ua-parser-js library to split it into clean, labelled fields: browser, engine, operating system, device (vendor, model and type), and CPU architecture. You can paste a string from a log file, a bug report, or analytics data, or load your own browser's value with a single click.

Why parse user agents

Developers and analysts read user agents to understand who is visiting a site and how it should behave. A support engineer reproducing a layout bug needs to know the exact browser and version a user reported. An analyst segmenting traffic wants to group visits by operating system or device type. A QA tester confirming a compatibility fix wants to verify which engine — Blink, WebKit, Gecko — a string maps to. Parsing turns an opaque one-line string into structured data you can reason about, compare, and document. Note that user agents can be edited or spoofed by extensions, privacy tools, and bots, so treat the result as a strong hint rather than absolute proof of identity.

Private, local parsing

All parsing happens with in-browser JavaScript. The library is bundled directly into the page, so the string you paste is never uploaded to a server and the tool makes no external API calls. That is important when the user agents you are inspecting come from real production logs or customer reports, which you generally do not want to send to a third party. Paste freely, parse as many strings as you like, and copy the results into your ticket or notes — the data never leaves your device.