Habitica - Habitica is a free habit building and productivity application.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.
SuperBetter - Empower youth mental health through schools and sports
Things - Things is an easy to use task manager.