UADetector is a library to identify over 190 different desktop and mobile browsers and 130 other User-Agents like feed readers, email clients and multimedia players. In addition, even more than 400 robots like BingBot, Googlebot or Yahoo Bot can be identified.
Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; Googlebot/2.1; +http://www.google.com/bot.html) Safari/537.36
This UA string is currently resolved as
Browser
instead ofRobot
, although it clearly identifies itself as Googlebot.