Open source support ticket system simple, free, lightweight, open source, and easy to setup and use.

Trakdesk is a fully customizable customer support platform with all the bells and whistles you would need to provide exceptional customer support.

Ticket Tailor lets you sell tickets online.

PHPBack is an open source feedback system.

Request Tracker is a ticket-tracking system written in Perl used to coordinate tasks and manage requests among a community of users.

OTRS Business Solution is a first-class help desk software packed with exclusive features and excellent support.

Web Help Desk is a powerful and affordable ticketing and IT asset management software solution.

Kayako is a customer service software.

Brimir is an Open source ticket manager.