GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Apache OpenOffice - Apache OpenOffice is an open source, office document productivity suite.
MkDocs - Project documentation with Markdown.
Big Huge Labs Writer - Writer is a free online distraction free writing environment provided by Big Huge Labs.
Docusaurus - Easy to maintain open source documentation websites
Office Online - With Office Online you can view, edit, and share Word, Excel, PowerPoint, and OneNote files on your devices using a web browser, so you can work anywhere.