Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Actiontext - Todo.txt client for Windows 10
Org mode - Org: an Emacs Mode for Notes, Planning, and Authoring
Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
QOwnNotes - QOwnNotes is a free plain-text notepad with markdown support for Linux, Mac OS X and Windows, that works together with ownCloud Notes.
Wellness Video Fx - Educate and Attract Patients with Engaging Videos -- Make Your Patients Feel Important And Connected -- Mobile and Desktop Friendly -- Easy To Use -- If your business is in the medical field, this is for you!