Bugzilla is the leading open-source/free software bug tracking system, with high-profile installations at mozilla.org, GNOME, Red Hat, and NASA, among others. It features a comprehensive set of fields, attachment management, inter-bug dependencies, email notification of changes, a powerful query interface, reporting, and Web, XML, email, and console interfaces. It can be managed entirely using a Web-based UI. The user UI is customizable using templates.
RT is an industrial-grade trouble ticketing system. It lets a group of people intelligently and efficiently manage requests submitted by a community of users. RT is used by systems administrators, customer support staffs, NOCs, developers, and even marketing departments to track issues, outages, bugs, requests, and all kinds of other things at thousands of sites around the world.
PHP Trouble Ticket provides a centralized means of problem reporting and tracking in multi-user environments (medium to large companies, development groups, etc.). It helps direct problem reports to the responsible administrator(s), keeps track of the status of a problem being worked on, and offers an up-to-date list of recent changes applied. It aims to be widely configurable, easy-to-use even for those not technically inclined, and multi-language capable.
Ozibug is a platform-independent, Web-based bug tracking system that can be installed and run straight out of the box on any Java servlet capable platform. It can be used to manage the reporting of bugs and tracking of their progress from discovery through to resolution. It provides standard features such as file attachments, multiple module support, email notifications, custom reports, and RSS feeds. For those who require more flexibility, it also offers fine grained access control, database storage, pluggable authentication, an incoming mail gateway, and customizable appearance, email notifications, and reference data.
BATTS (Barnhard Associates Trouble Ticketing System) is a lean, elegant trouble ticket system with both command line and Web interfaces, written in Perl. It uses MySQL for its backend, and has a ticket-via-email interface for submission and informational logging. Features include support for tickets pending on or resolved when other tickets are disposed of, an ability to assign tickets to a person, an ability to categorize and prioritize tickets, and associating billing codes with various logging events.
Bugzero is a Web-based change management and issue tracking system used in a distributed team environment to track software bugs, hardware defects, test cases, or any other issues. It can also be used equally well as a helpdesk customer support, trouble ticketing, or email management system to collect and manage customer feedbacks, incidents, requests, and issues. It is easy to use, but still flexible and adaptive, and can be configured to fit to your organization's unique business process and workflow.
ITracker is a Java J2EE issue/bug tracking system designed to support multiple projects with independent user bases. It supports features such as full i18n support, multiple versions and project components, detailed histories, issue searching, file attachments, dynamic reports with charts, configurable field values, customizable project level fields, pluggable authentication, a built-in scheduler, and email notifications.
Copper is a Web-based project management software tool designed to help creative teams manage clients, projects, tasks, files, budgets, and events. It has an HTML/AJAX front end. It is available with full source for a licence fee or as a SAAS hosted service (compatible with iPhone, but available via PC/Mac/Linux and a Web browser).
Issue-Tracker is a support issue tracking system. The system is written to be user-friendly and is built around a modular API to make it easy to add to if need be. It includes many features that can help customer/technical support organizations resolve issues quickly and easily. These features include things like file uploads, email parsing, unlimited users and groups, email and SMS notifications, group and user reporting, and much more.