The Free / Libre / Open Source Web App with the most built-in features
PukiWiki is used by many users, a light and high functional Wiki clone
WackoWiki is a light and easy to install multilingual Wiki-engine.
The Free & Popular MediaWiki Web Software in Complete Virtual Machine
Open Source Enterprise Wiki and Web Application Platform
Embeddable/J2E/Desktop Java Wiki CMS
Piggydb helps you have more fun with knowledge creation.
Web-based knowledge base template.
Lightweight extensible wiki engine
Umbraco alternative 8, .NET CMS forum & wiki multi site/domain
doc cms + more
Open source platform to write and publish print and digital books
Wiki .net is a simple and open source wiki engine running on Asp.Net