Most commercial defect-tracking software vendors charge enormous licensing fees. Despite being “free”, these open source defect tracking systems have many features its expensive counterparts lack.
Continue reading about List of Open Source Defect Tracking Systems
eTraxis is a free (GPL licensed) issues tracking web-based system with unlimited number of fully customizable workflows.
MyTracker is tracking and collaboration system that allows users to collect, file, share, and discuss any type of information, whether it is news, a thought, bug, task, idea, document, graph and report. MyTracker is powerful, well-organized, efficient, fully customizable and easy to use.
]project-open[ is a Web-based Project Management / Project-ERP software for organizations with 2-2000 users. ]po[ integrates areas such as CRM, sales, project planning, project tracking, collaboration, timesheet, invoicing and payments. 
AVS is a free SCM software based on the main concepts provided by the most expensive alternatives available on the market place. It includes a task based file repository management system, and a bug tracking engine. AVS is released with most of its features free, while a few extended ones are restricted by a commercial licence.