MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
Document360 - Self-service knowledge base software focused on SaaS Products & Enterprise Software Projects.
TiddlyWiki - a non-linear personal web notebook
ProProfs Knowledge Base - ProProfs Knowledge Base is a cutting-edge knowledge management software that assists businesses to reduces support tickets by self-help and create online manuals, guides, wikis, documentation, FAQs and more.
Confluence - Confluence is content collaboration software that changes how modern teams work
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.