Mantis Bug Tracker: Free and open source software, World Wide Web, tracking system, GNU General Public License, Software bug, Issue system

Concurrent Versions System: Free software, Software development, Collaboration, Dick Grune, Open source...

Xena (Software): Open Source Software, Dspace, GNU General Public License

Flyspray (bug tracking software): PHP, GNU Lesser General Public License, Psi (instant messaging client)

KForge: GNU General Public License, Open Source Software, Knowledge Foundation