Mantis is a web-based bugtracking system.

phpBugTracker is a web-based bug reporting and tracking system. It allows bugs to be tracked throughout the development life cycle, providing a convenient interface for searching through a bug database and generating summary reports on bug data.

Eventum is a user-friendly and flexible issue tracking system that can be used by a support department to track incoming technical support requests, or by a software development team to quickly organize tasks and bugs.

Bosco is a rewrite of the popular Bugzilla defect tracking software in PHP. Among its goals are database-independence and ease of maintenance and modification. An API is also planned to allow external applications to work with Bosco's data.

A re-write based loosely around the php.net bugs system that uses the FlexyFramework logic.

The BugPort system is an open-source, freely available, web-based system to manage tasks and defects throughout the software development process.