About the User Agent Parser
This user agent parser reads the User-Agent header that browsers, apps and bots send with every request and translates it into plain facts: which browser and version (Chrome, Safari, Firefox, Edge, Samsung Internet, Opera and more), which rendering engine (Blink, WebKit, Gecko), which operating system and version, whether the device is a desktop, phone, tablet, TV or console, and whether the visitor is a crawler such as Googlebot, Bingbot or GPTBot. Your own browser’s user agent is shown and parsed automatically.
It is handy for reading server logs and analytics exports, debugging device-specific bugs reported by users, checking how a bot identifies itself, and writing or testing user-agent rules. A token table explains the confusing parts — why almost every UA starts with "Mozilla/5.0" and why Chrome claims to be Safari.
User agents are easy to fake and increasingly reduced: Chrome and Edge now freeze the reported Windows version at "NT 10.0", macOS at 10_15_7 and hide Android device models, so this tool cannot distinguish Windows 10 from Windows 11. For reliable details use the User-Agent Client Hints API, and use feature detection rather than UA sniffing in your code.
How to use the user agent parser
- 1Look at the panel above to see your own browser’s user agent parsed.
- 2To analyse another one, paste the user-agent string from a log or request header.
- 3Read the browser, version, OS and device type.
- 4Check the token table to understand each part of the string.
- 5Read the notes about frozen or reduced values before relying on OS versions.
Formula and method
A user-agent string is a list of product tokens (name/version) plus parenthesised comments, as defined for the HTTP User-Agent header in RFC 9110. Because browsers copied each other’s tokens for compatibility, the parser checks rules in a careful order: bots and tools first, then specific browsers that embed other names (Edge, Opera and Samsung Internet all contain "Chrome", and Chrome contains "Safari"), and only then the generic Chrome and Safari rules.
The operating system comes from the platform comment (Windows NT 10.0, Mac OS X 10_15_7, iPhone OS 17_6, Android 14), with Windows NT versions mapped to marketing names. Device type is inferred from tokens such as iPad, Mobile, TV and console names; an Android UA without "Mobile" is treated as a tablet, following Google’s guidance. The engine is Blink for Chromium browsers, Gecko for Firefox, and WebKit for Safari and every browser on iOS.
Worked examples
Chrome on Windows
The string contains Chrome/129.0.0.0 and no more specific browser token, so it is Chrome 129. "Windows NT 10.0" maps to Windows 10 or 11 (Chrome reports the same value for both) and "Win64; x64" means a 64-bit build. The AppleWebKit and Safari tokens are only there for compatibility; the engine is Blink.
Safari on iPhone
Safari has no "Safari/version" number of its own — its version comes from Version/17.6. The platform comment says iPhone OS 17_6, which is iOS 17.6, and the iPhone token makes it a mobile device using WebKit.
Samsung Internet on a Galaxy phone
SamsungBrowser/25.0 is checked before the generic Chrome token, so it is identified as Samsung Internet 25 built on Chromium 121. Android 14 with "Mobile" means a phone, and the model SM-S918B is a Samsung Galaxy S23 Ultra.
Googlebot crawler
The Googlebot/2.1 token identifies Google’s web crawler. Because anyone can copy this string, confirm genuine Googlebot traffic with a reverse DNS lookup that resolves to googlebot.com or google.com.
Frequently asked questions
What is my user agent?+
Your user agent is the text your browser sends in the User-Agent header with every request. The panel at the top of this page reads it from navigator.userAgent and parses it into browser, version, operating system and device type.
Why does every user agent start with Mozilla/5.0?+
In the 1990s servers sent advanced pages only to Netscape (code-named Mozilla). Other browsers added "Mozilla" to receive the same pages, and the token has stayed for compatibility ever since. It carries no information today.
Can I tell Windows 11 from Windows 10 by the user agent?+
No. Both report "Windows NT 10.0". Chromium browsers expose the real version through the Sec-CH-UA-Platform-Version client hint: values of 13 or higher indicate Windows 11.
Why does Chrome’s user agent mention Safari and AppleWebKit?+
Chrome was originally built on WebKit, Safari’s engine, and kept those tokens so sites that sniff for Safari or WebKit would serve it full-featured pages. Chrome has used its own Blink engine since 2013.
Is user-agent detection reliable?+
Not fully. Users and bots can set any string, and browsers are reducing the detail they send. Use feature detection for functionality, Client Hints for device details, and reverse DNS to verify crawlers.