GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
MkDocs - Project documentation with Markdown.
Docusaurus - Easy to maintain open source documentation websites
Docsify.js - A magical documentation site generator.
Doxygen - Generate documentation from source code
Archivy - A self-hosted knowledge repository that allows you to safely preserve useful content that contributes to your own personal, searchable and extensible wiki.