Bugzilla is one example of a class of programs called "Defect Tracking Systems", or, more commonly, "Bug-Tracking Systems". Defect Tracking Systems allow individual or groups of developers to keep track of outstanding bugs in their product effectively. Read more hot
Bug-A-Boo is an open source bug tracking system for your web server. Some of its features are email notifications, fulltext indexing, no limits in everything, query storage, individual themes, etc.
Bugnicar is a bugtracking system using email to manage the bug database.
bz2gnats is responsible for getting bugs from the bugzilla database (used in bugzilla which is a bug tracking system) and changing their format to a text format so that the bugs may be used in Gnats database.
DisTract is a distributed bug tracker. DisTract allows you to manage bugs in a distributed and potentially offline manner through your Web browser on your local machine. The distribution is achieved by making use of a distributed software control system, Monotone.
Feature Kong is a collaborative web database that tracks changes. It was originally intended for software feature planning but can be easily reconfigured for other purposes.
fixx bug tracker
fixx is a bug tracking and issue tracking system for software teams in the enterprise. By focusing on the needs of software developers and their managers, fixx enables you to collaborate, painlessly resolve bugs, and deliver quality software on time.
GNU GNATS is a set of tools for tracking bugs reported by users to a central site. It allows problem report management and communication with users via various means. GNATS stores all the information about problem reports in its databases and provides tools for querying, editing, and maintenance of the databases.
gwyple is a GUI, implemented in Perl and Perl/TK, for handling bug reports.
InDefero is a software forge. It can be used to save you and your team time. It tracks bugs and provides downloads, documentation, and an easy overview of your code base.
(commercial) The jab:ITS PHP/MySQL Incident Tracking System for Intranets provides a browser-based means of tracking and reporting customer support/help issues and occurrences
PRepS is an easy to use problem tracking system. A similar idea to Gnats, but much more GUI based. It requires PostgreSQL and GTK.
Stabilizer is a system that aims to quickly stabilize buggy GUI applications so that people can get real work done with them. Users can collaboratively and quickly stabilize applications simply by using them normally and reporting any bugs that they encounter to prevent anyone (including themselves) from encountering them again.
Wastebug is a minimalistic, yet usable bug manager. It's main design principles are simplicity and usability. It will probably always lack many of the features that managers, control freaks and methodologists want; it's designed for developers instead.
workbench is a php/mySQL bug tracking application. It supports multiple projects, full change history, custom reporting and many other useful tools.
YakTrack is a lightweight, open-source issue-tracking database system written in Python.