Workflowy - A better way to organize your mind.

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.

Orgzly - Outliner for notes, tasks and to-dos

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.

UV Outliner - UV Outliner is a small and powerful single-pane outliner.

Wondershare PDFelement - All-in-one PDF editor