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.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
HabitBull - HabitBull
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Slack - A messaging app for teams who see through the Earth!