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.
Nifty - Manage projects, work, and communications in one place.
Habitica - Habitica is a free habit building and productivity application.
Intercom on Product Management - The ultimate resource for aspiring product managers
HabitBull - HabitBull
Party Line - Use Slack to manage your projects
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.