Scribes - A text editor for GNOME that combines simplicity with power.
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.
Big Huge Labs Writer - Writer is a free online distraction free writing environment provided by Big Huge Labs.
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.
Caret - Better Markdown Editor for Mac / Windows / Linux
Wondershare PDFelement - All-in-one PDF editor