AceProject: Offers free web-based software for project management, bug tracking and timesheet management.
AdminLog: AdminLog is a general purpose data management utility for bug tracking, personal task management and even project level management across a large group.
Agstools: BugTrack, simple free bugtracking system based on perl5 and any DBI compliant database.
Bug-A-Boo: An open source bug tracking system running on any web server allowing the execution of tdbengine binaries. It is dristributed unter the terms of the GPL.
Bugs Online: A free (GPL) bug tracking system for use with Microsoft IIS, Access and ASP.
BugTracker.NET: Opensource web-based bug tracker written using ASP.NET and C#.
Bugzilla: Bug tracking used by the Mozilla projects. Inherently web-based, written in Perl, and uses MySQL as its database back-end. Open-Source. Updates available via CVS.
Debian Bug Tracking Software: GPL'd Perl-5 scripts which maintain a database of problem reports. Input by email, listings via webserver.
elementool: A free bug tracking and managing tool, on the Web, supported by advertisements. Helps developers and testers to track and manage bugs and features. Installation is not required.
Elips: A web-based free bug tracker written in Java-Jsp.
GIFFT: Web based bug tracking system running on Windows, Linux, Unix as a CGI for Apache or other web server.
IssueTrackerProduct: Open-source web-based issue/bug tracker, written in Python.
JitterBug: A web based bug tracking system, originally developed by the Samba Team to handle bug tracking, problem reports and queries, now available under the GNU General Public License. Operates like a communal Web based email system - no database back end required.
Keystone: Data stored in a SQL database, accessed by any Web browser which understands forms, tables, and cookies. By StoneKeep consulting. Free for under 10 users.
Mantis: php/MySQL/web based bugtracking system.
phpBugTracker: A web-based bug tracking system built in PHP.
Request Tracker: A free bug tracking and trouble ticketing system
Roundup: A simple-to-use and -install issue-tracking system with command-line, web and e-mail interfaces.
Teamatic: Free web-based bug tracking, ticketing and project resource tracking system. Designed to meet the requirements of most Information Technology, Consulting and Engineering projects.
Trac: Trac is a web-based software project management and bug/issue tracking system. It provides an interface to Subversion and an integrated wiki.
TrackTask: A free browser-based issue tracking tool.
WREQ: Work Request, a distributed request/problem tracking system, written in Perl 5. Access by Web or email.