WhatWeb next generation web scanner identifies what websites are running. Released at the Kiwicon conference (kiwicon.org) in Wellington, New Zealand. Written in Ruby for Linux. Flexible plugin architecture with over 60 plugins so far. Passive plugins use information in the headers, cookies, HTML body and URL. Aggressive plugins can identify versions of Joomla, phpBB, etc by making extra requests to the webserver.
You can download it from the following link: https://packetstormsecurity.com/files/download/83341/whatweb-0.3.tar.gz
Source: https://packetstormsecurity.com/files/83341/WhatWeb-Scanner-0.3.html