FreeScout is the perfect help desk solution for those who need to provide a professional customer support, but who can not afford to pay for Zendesk or Help Scout.
PmWiki is a wiki-based content-management system (CMS) for collaborative creation and maintenance of websites. Page editing can be left open to the public or restricted to small groups of authors.
Live support for your website. Featuring web and desktop clients. XMPP notifications support including GTalk, Android, IPhone. Enables interactive live chat for customers support.
Hesk allows you to setup a ticket based support system for your website. Your customers are able to submit support tickets and the staff has a nice web based interface to reply to and manage tickets.
Mibew Messenger (also known as Open Web Messenger) is an open-source live support application that enables one-on-one chat assistance in real-time directly from your website.
osTicket is a widely-used and trusted open source support ticket system. It seamlessly routes inquiries created via email, web-forms and phone calls into a simple, easy-to-use customer support platform.
MediaWiki is a free and open source software wiki package written in PHP, originally for use on Wikipedia. It is now also used by several other projects of the non-profit Wikimedia Foundation and by many other wikis.
WackoWiki is a small, lightweight, handy, expandable, multilingual Wiki-engine. It's designed for speed and extensibility. Includes a WYTIWYG editor, easy installer and many localizations.
phpMyFAQ is a multilingual, completely database-driven FAQ-system based on PHP and MySQL. phpMyFAQ also offers a Content Management-System with a WYSIWYG editor and an image manager.
Question2Answer is a free PHP/MySQL solution for social Q&A sites (like Stack Overflow or Stack Exchange) with the following features: Five minutes to install, Easy styling with CSS themes...
HelpDeskZ allows you to manage your site's support with a web-based support ticket system. Categorize tickets into groups to organize tickets and assign agents to groups to manage tickets.
OpenSupports is a support center for your website. You can create staff members who will help you to answers user's tickets. Also, you can have an articles library for your users.
LionWiki is minimalist file-based, templatable, extensible wiki engine which works from just one file. It's intended for small personal websites, notebooks and other simple applications.
DokuWiki is a standards-compliant, simple-to-use Wiki mainly aimed at creating documentation of any kind. It is targeted at developer teams, workgroups, and small companies.