OTRS
  Issue tracking system
  Bug tracking system
  Comparison of issue-tracking systems
  Launchpad (website)
  Fossil (software)
  GNATS
  Runbook
  Lisog
  Comparison of help desk issue tracking software
  Debian bug tracking system
  Request Tracker
  Zentrack
  Redmine
  LibreSource
  Help desk
  Mantis Bug Tracker
  Distributed revision control
  Flyspray (bug tracking software)
  Roundup (issue tracker)
  Ikiwiki
  Bugzilla
  The Bug Genie
  Trac