User agent string parser in golang
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Fix module package name
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User agent parsing

Build Status

useragent is a library written in golang to parse user agent strings.


First install the library with:

go get

useragent is simple to use. First parse a string with useragent.Parse and then access the fields of useragent.UserAgent for the required information. Example:

See godoc for the complete documentation.

How it works?

      Lasciate ogne speranza, voi ch'intrate. -Dante

Parsing user agent strings is a hell. There is no standard for user agent strings, so useragent must use some heuristics. The site has been invaluable during development. Some relevant links are also:

for the supported user agents see:

If you think useragent doesn't parse correctly a particular user agent string, just open an issue :).

Why this library?

useragent doesn't just split the user agent string and look for specific strings like other parsers, but it has specific parser for the most common browsers/crawlers and falls back to a generic parser for everything else. Its main features are:

  • Simple and stable API.
  • High precision in detection of the most common browsers/crawlers.
  • Detects mobile/tablet devices.
  • OS detection.
  • URL with more information about the user agent (usually it's the home page).
  • Security level detection when reported by browsers.


Thanks a lot to @brendanwalters (from for the contributions.



useragent is released under the GPLv3 or later, see COPYING.