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.
Pages - Pages for Mac is a word processor that offers tools needed to create documents.
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.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
Wondershare PDFelement - All-in-one PDF editor
Dropbox Paper - A collaborative document-editing service