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.

Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.

Docusaurus - Easy to maintain open source documentation websites

Wondershare PDFelement - All-in-one PDF editor