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.
Aspose.Slides for Cloud - Use cURL commands to create, manipulate, merge, split & convert PPT PPTX presentations & slides to PDF, XPS, TIFF, ODP, OTP, HTML & other formats.
Microsoft Word - Microsoft Word is a commercial word document processor for Windows.
GitPitch - The Markdown Presentation Service on Git
AbiWord - AbiWord is a free software word processor.
PPTX Viewer - PPTX Viewer is one of the lightweight applications that allows you to view, create, edit and share your presentation without facing any advertisement issue.