Mantis Bug Tracker is a free and open source, web-based bug tracking system. It is written in the PHP scripting language and works with MySQL, MS SQL, and PostgreSQL databases and a webserver. MantisBT can be installed on Windows, Linux, Mac OS, OS/2, and others. Almost any web browser should be able to function as a client.
Moreover MantisHub is available as commercial hosted solution of MantisBT.
Supports any platform that runs PHP (Windows, Linux, Mac, Solaris, AS400/i5, etc)
Available in 68 localizations.
Customizable Issue Pages
Multiple Projects per instance
Support for Projects, Sub-Projects, and Categories.
Users can have a different access level per project
My View Page
Search and Filter
Full Text Search
Shared Filters (across users / projects)
Built-in Reporting (reports / graphs)
Users can monitor specific issues
Attachments (can be saved on webserver or in database - can also backup to an FTP account)
Issue Change History
RSS Feeds (news, issues matching saved filters, issues matching a specific project)
Customizable issue workflow
Sponsorships Support - users are able to place bounties or sponsorships for specific issues, also developers can track such sponsorships / payments.
Signup with Captcha and Email Confirmation.
Self-Service Reset Password Support
Export to csv, Microsoft Excel, Microsoft Word
Ability to extended functionality through hook (custom) functions.
Ability to extended functionality through plugins.
Reporting issues via Email (available as a patch for 1.1.x and EmailReporting Plugin for 1.2.x]])
Reporting Issues via a custom form on your website (Anonymantis).
Source Control Integration (GIT, SVN and CVS).
No limit on the number of users, issues, or projects.
Wiki Integration (optional)
Ability to send messages to messages to other users in regards to a specific issue.... More Info »