Habitica - Habitica is a free habit building and productivity application.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.
Simplenote - The simplest way to keep notes. Light, clean, and free. Simplenote is now available for iOS, Android, Mac, and the web.
Loop Habit Tracker - Loop Habit Tracker (AKA uhabits) helps to create and maintain good habits in order to achieve their...
Laverna - Laverna is a JavaScript note taking application with Markdown editor and encryption support.