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.
Fitbod - Personalized Strength-Training powered by Machine Learning
Habitica - Habitica is a free habit building and productivity application.
MyFitnessPal - Track the number of calories that you consume each day with MyFitnessPal. The app also lets you create a diet and track the exercise that you complete each day whether it's walking, running or some other type of program.
HabitBull - HabitBull
Fitocracy - Fitocracy is a social network that turns exercise into a cooperative and competitive exercise with friends, rivals, and strangers.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.