Edtr.io - Intuitive WYSIWYG web editor, open source & fully adaptable.
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.
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
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.
MathType - The Professional version of Equation Editor- MathType is a powerful interactive tool for Windows and Macintosh that lets you create mathematical notation for word processing, web pages, desktop publishing, presentations, and for TeX, LaTeX, and Math…
Wondershare PDFelement - All-in-one PDF editor