MantisBT is a popular free web-based bug tracking system.
Stratford Web Design offers installation, support and hosting for Mantis instances.
MantisBT is a free popular web-based bugtracking system (feature list). It is written in the PHP scripting language and works with MySQL, MS SQL, and PostgreSQL databases and a webserver. MantisBT has been installed on Windows, Linux, Mac OS, OS/2, and others. Almost any web browser should be able to function as a client. It is released under the terms of the GNU General Public License (GPL).
A demo of Manits bug tracker be be seen here: http://www.mantisbt.org/demo/
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