User Agent Parser

How to use the user agent parser

1. Your own user agent appears automatically.
2. Paste a different string to inspect it.
3. Read the parsed browser, engine, OS and device.

About this tool

A user agent string is a historical artefact more than a description. Almost every browser still starts with “Mozilla/5.0” — a compatibility claim from the 1990s that nobody dares remove — and Chrome additionally claims to be Safari and KHTML, because sites once checked for those.

This parses the string into the pieces that matter: browser and version, rendering engine, operating system, device type, and whether it looks like a bot. Useful for reading a log line or a support request.

What it should not be used for is deciding what your code does. Browsers can and do change their user agent, and a string that lies about its identity still cannot fake whether an API exists — so test for the feature instead. User-agent sniffing is precisely how sites end up broken in browsers nobody tested.

Common uses

• Identifying the browser behind a support report.
• Reading user agents out of a server log.
• Checking what your own browser reports.

Frequently asked questions

Why does every browser claim to be Mozilla?

A 1990s compatibility hack that stuck. Sites checked for 'Mozilla' to serve modern HTML, so every browser started claiming it, and none has been able to stop.

Should I use the user agent to detect features?

No. Check whether the feature exists instead. User agents can be changed freely, and sniffing breaks sites for browsers the author never tested.