Request Tracker - issue tracking system in CGI and Perl

Request Tracker (RT) is an enterprise-grade issue tracking system which thousands of organizations use for bug tracking, help desk ticketing, customer service, workflow processes, change management etc. This product is very stable and been around for over 10 years.

It has loads of features like Dashboard support, Seamless PGP support for mails, Richtext editing, Time tracking etc. It has support of more than 15 languages. RT provides a REST API and even a command-line client to talk to RT from other programs and integrate with other systems.