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
JTrac is a generic issue-tracking web-application that can be easily customized by adding custom fields and drop-downs. Features include customizable workflow, field level permissions, e-mail integration, file attachments and a detailed history view.
Flyspray is an uncomplicated, web-based bug tracking system for assisting with software development, written in PHP.
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