GitLab - Create, review and deploy code together with GitLab open source git repo management software | GitLab
Redmine - Flexible project management web application
Lean Testing - Lean Testing is a free bug tracker and test case management software for high performance development teams
Mantis Bug Tracker - Mantis Bug Tracker is a free and open source, web-based bug tracking system.
Phabricator - Phacility - Phabricator
The Bug Genie - The Bug Genie is an issue tracking and project management, completely free for small teams.