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

First install the library with:

go get xojoc.pw/useragent

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:

• Access fields

see godoc for the complete documentation.

      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 http://www.useragentstring.com/ has been invaluable during development. Some relevant links are also:

• https://developer.mozilla.org/en-US/docs/Web/HTTP/Gecko_user_agent_string_reference
• https://developer.chrome.com/multidevice/user-agent
• https://developer.apple.com/library/safari/documentation/AppleApplications/Reference/SafariWebContent/OptimizingforSafarioniPhone/OptimizingforSafarioniPhone.html#//apple_ref/doc/uid/TP40006517-SW3
• http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/internet-explorer-11-user-agent-string-ua-string-sniffing-compatibility-with-gecko-webkit.aspx

for the supported user agents see:

• browsers: browser.go
• crawlers: crawler.go

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

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 its the home page).
• Security level detection when reported by browsers.

useragent was written by Alexandru Cojocaru (http://xojoc.pw) and uses blang/semver to parse versions.

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