Bugzilla

Bugzilla is a Web-based general-purpose bugtracker and testing tool originally developed and used by the Mozilla project, and licensed under the Mozilla Public License.

Released as open source software by Netscape Communications in 1998, it has been adopted by a variety of organizations for use as a bug tracking system for both free and open source software and proprietary projects and products. Bugzilla is used, among others, by Mozilla Foundation, Wikimedia Foundation, WebKit, NASA, Yahoo!, GNOME, KDE, Red Hat and Novell.

Read more about Bugzilla:  History, Requirements, Design, Zarro Boogs