Open Source Project Management Defect Tracking Tools

Trac - Open source enhanced wiki and issue tracking system by Edgewall Software.
Own description: "The Trac Project"
Bugzilla - Open Source Bug Tracking System.
Own description: "Home :: Bugzilla :: bugzilla.org"
GNATS - GNU defect tracking tool.
Own description: "GNATS - GNU Project - Free Software Foundation (FSF)"
Mantis - Open source bug tracking system.
Own description: "MantisBT is a popular free web-based bug tracking system. It is written in PHP works with MySQL, MS SQL, and PostgreSQL databases. MantisBT has been installed on Windows, Linux, Mac OS, OS/2, and others. It is released under the terms of the GNU Genera..."
Redmine - Open source project management and bug tracking tool written in Ruby.
Own description: "Redmine"
Flyspray - Open source bug tracking tool.
Own description: "start - Flyspray - The Bug Killer!"
JTrac - Open source issue-tracking application.
Own description: "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."
Request Tracker - Open source issue tracking system written in Perl by Best Practical.
Own description: "RT: Request Tracker - Best Practical"
Scarab - Open source issue tracking tool.
Own description: "CollabNet, Facilitating Collaborative Software Development"
BugTracker.NET-  Open source bug tracking tool based on ASP.NET, C#, and Microsoft SQL Server.
Own description: "BugTracker.NET Home - Free Bug Tracking"
Ditz - Open source distributed issue tracker designed to work with distributed version control systems written in Ruby.
Own description: "Ditz"
Eventum - Open source bug tracking system developed by the MySQL Technical Support team.
Own description: "MySQL :: Eventum Issue / Bug Tracking System"
PhpBugTracker- Open source bug tracking tool.
Own description: "phpBugTracker - open source issue tracking software"
Project Open - Open source project management and issue tracking tool.
Own description: "]project-open[ is an Open Source Project Management/ERP tool"
Bugs - The Bug Genie - Open source defect tracking tool based on PHP/MySQL.
Own description: "Get The Bug Genie at SourceForge.net. Fast, secure and free downloads from the largest Open Source applications and software directory"
WebIssues Open source issue tracking and team collaboration tool written in PHP by Michal Mecinski.
Own description: "WebIssues | Issue tracking and team collaboration system"
AVS - Advanced Versioning System - Open source configuration management system embedding a bug tracking tool.
Own description: "software configuration management with integrated bug tracking engine, 100% java client deployed through JNLP"
MyTracker - Open source defect tracking and collaboration system.
Own description: "myTracker Home page"