Trac - Trac is a project management and bug/issue tracking system. Provides an interface to Subversion and an integrated wiki.
jtrac - JTrac is an open source and highly customizable issue-tracking web-application written in Java.
Pivotal Tracker - Pivotal Tracker: The awesome, lightweight, agile project management tool for software teams. Get your 30-day Free Trial started today!
Traq - Traq is a PHP powered project manager and issue tracker featuring multiple projects, milestones...
Gitea - A painless self-hosted Git service
Bugify - Bugify is a simple PHP issue tracker, designed to offer powerful bug tracking capabilities in an easy to use system.