MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
AMuseWiki - Amusewiki is more than just a wiki engine, it’s also a powerful authoring, archiving and publishing platform.
Ema Personal Wiki - Ema Personal Wiki uses Markdown to freely create and manage structured notes, like a website.
Bloomfire - Let Bloomfire help you get organized! Organize your content, build your company knowledge base and help your employees to be more successful.
Pmwiki - PmWiki is a wiki-based system for collaborative creation and maintenance of websites.
BetterDocs - Create & Manage Knowledge Base Documentation Effectively To Reduce Support Tickets, Increase productivity & User Experience with BetterDocs.