Test & requirements management
TestLink is a web based Test Management tool. The application provides Test specification, Test plans and execution, Reporting, Requirements specification and collaborate with well-known bug trackers. Repository: https://github.com/TestLinkOpenSourceTRMS
This project is no longer maintained or active. Sourceforge refuses to remove it from their listing after 5 years of asking.
Flyspray is an uncomplicated, web-based bug tracking system for assisting with software development, written in PHP.
KM is a Project Portfolio, Issue Management, Change Management, Trouble Ticketing, Testing (White, Black, Integration, Regression), Q.A, Open Source integrated and customizable Web based solution which can easily implemented and customized.
Issue tracking and team collaboration system
WebIssues is an open source, multi-platform system for issue tracking and team collaboration. It can be used to store, share and track issues with various attributes, description, comments and file attachments. The system is easy to install and use but has many capabilities and is highly customizable. Website: https://webissues.mimec.org/ The current development version of WebIssues can be found at https://github.com/mimecorg/webissues