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.
Vanido - Vanido is a singing coach in your pockets.
HabitBull - HabitBull
Singscope - See your pitch analyzed as you sing
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Listening Singing Teacher - Listening Singing Teacher helps you to sing in tune and in rhythm.