Habitica - Habitica is a free habit building and productivity application.
GoalsWon - Human accountability coaching for busy people
Loop Habit Tracker - Loop Habit Tracker (AKA uhabits) helps to create and maintain good habits in order to achieve their...
Beeminder - Beeminder
ActivityWatch - Log what you do on your computer. Simple (yet powerful), extensible, no third parties.
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.