Bugzilla is a Web-based bug tracking application.
MantisBT is a free popular web-based bugtracking system
"Since mantis is a bit more complete than bugzilla when it comes to features you could define separate issues with custom field for your tasks"
from question "What is an easy Mylyn task repository to use for a small (~40 devs) project?"
"Research showed me that mantis is simpler to use over bugzilla so i decided to use mantis but have no idea how to install it.can anyone please tell me what are the steps you need to take in order to install mantis bug tracking system in a small company to track website mobile portal bugs"
from question "Mantis Bug Tracking system"