phpMyFAQ - phpMyFAQ is a world’s most popular mobile-friendly, feature-rich and open-sources FAQ software that uses PHP 5.
Issuetrak - Issue tracking software for help desk and customer service
Phaseware Self Service Center - Self Service center allows incident submission, access to knowledgebase, FAQs, and crowdsourcing through forums and communities.
Deskun - Deskun is a Help Desk system inside Gmail. It enables you to support customers directly from your mailbox, manage projects, and use free features for Gmail.
iService - iService is an integrated solution for managing all customer interactions with complete web-based interface, routes and automatically responds to customer email, provides a simple but powerful knowledge base, and includes a complete contact manageme…
Kapdesk - Kapdesk offers support teams with a helpdesk software to streamline support tasks.