The Free / Libre / Open Source Web App with the most built-in features
KBPublisher is Knowledge Management Software.
SCADA HMI for substations, IoT and automation applications
HelpDEZk is a powerfull software that manages requests/incidents.
Vimat Is More than A To-do list
An open source, web based, platform independent knowledge base system.
The Halo extension extends MediaWiki and Semantic Mediawiki