Habitica - Habitica is a free habit building and productivity application.
Button for Google Calendar™ - See your daily schedule and join meetings in one-click.
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Loop Habit Tracker - Loop Habit Tracker (AKA uhabits) helps to create and maintain good habits in order to achieve their...
Calndr.link - Dead simple & free add to calendar links + API