User Agent Parser

How to parse a user agent string

1. Paste a user agent string into the box. When the page opens, it already contains the user agent of the browser you are using now.
2. Click Parse. The result also updates while you type.
3. Read the browser, engine, operating system, device and CPU architecture in the result cards. Bot or crawler tells you whether the string belongs to a known search engine crawler, monitoring service or command-line client.
4. To analyse your own browser as precisely as possible, click Use my browser. In Chrome, Edge, Opera and other Chromium browsers, this also reads the User-Agent Client Hints, which give the real platform version, CPU architecture and phone model.
5. To analyse many strings at once, paste one user agent per line (from a server log, for example). The tool switches to a table with one row per line. Click Download CSV to save the results for a spreadsheet.

Everything runs locally with the open-source ua-parser-js library: the strings you paste are never sent anywhere.

What a user agent string contains

A user agent is the text a browser sends in the User-Agent HTTP header and exposes as navigator.userAgent. It is a historical patchwork rather than a clean format. Almost every browser starts with Mozilla/5.0 for compatibility reasons, and Chrome still mentions AppleWebKit and Safari. The parser therefore matches known patterns in a precise order instead of reading tokens at face value:

• Browser: the product and its version, such as Chrome 131, Firefox 128 or Mobile Safari 17.5. Browser type is filled for special clients: crawler, command-line tool, email client, in-app browser or media player.
• Engine: Blink (Chrome, Edge, Opera, Samsung Internet), Gecko (Firefox) or WebKit (Safari and every browser on iOS).
• Operating system and its version, when the string reveals it.
• Device: type (mobile phone, tablet, smart TV, console, wearable…), vendor and model. Desktop browsers usually carry no device token, so the tool shows “Desktop (no device token)” when a desktop OS is found.
• CPU architecture, such as amd64 or arm64, when mentioned.

Reduced and frozen user agents

Since 2022–2023, Chromium browsers send a reduced user agent to limit passive fingerprinting. The major version is still real, but the minor version is always 0.0.0 (Chrome/131.0.0.0), and the platform part is frozen:

• Windows NT 10.0; Win64; x64 on every Windows version, including Windows 11;
• Macintosh; Intel Mac OS X 10_15_7 on every macOS version, even on Apple silicon Macs;
• Linux; Android 10; K on every Android phone: the real Android version and model are hidden.

Safari has frozen its macOS version for years too, and Firefox reports Windows NT 10.0 on Windows 11. When the tool recognises one of these frozen patterns, it shows a note: the parse is correct, but the string simply does not contain the details any more.

The replacement is User-Agent Client Hints. A server asks for extra values with the Accept-CH header and receives Sec-CH-UA, Sec-CH-UA-Platform, Sec-CH-UA-Platform-Version or Sec-CH-UA-Model request headers; scripts call navigator.userAgentData.getHighEntropyValues(). Use my browser does exactly that and lists the values under the Client Hints heading.