Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
MkDocs - Project documentation with Markdown.
Askalot - Askalot is a next generation CQA (Community Question and Answer) system.
Docusaurus - Easy to maintain open source documentation websites