GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.

Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

MkDocs - Project documentation with Markdown.

Microsoft Word - Microsoft Word is a commercial word document processor for Windows.

Docusaurus - Easy to maintain open source documentation websites

Apache OpenOffice Writer - Open-source word processor of the Apache OpenOffice suite.