I guess it's really safe cause it's open source, you can make notes on your habits but don't really do that. Its simple. Really fast. Haven't found a way to connect it to notion. In general it's a great app to track you habits. Does its job. Not more, not less.
Habitica - Habitica is a free habit building and productivity application.
Habits - Habits is an Android app that I wrote to help me work towards my goals by turning them in to habits.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
HabitBull - HabitBull
Habits by Reclaim.ai - Auto-block time on your calendar for all your routines
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.