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.
iSpring Free - iSpring Free is a free eLearning authoring tool that allows you to create responsive courses and quizzes right in PowerPoint and convert them to HTML5 or SCORM.
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.
E.M. PowerPoint Video Converter - E.M. PowerPoint Video Converter is an all-in-one PowerPoint to video converter.
Wondershare PDFelement - All-in-one PDF editor
Slidego - At SlideGo we regard presentation software like Powerpoint as a universal authoring tool.