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.
BeeLine reader - Read faster with this visual hack.
Habitica - Habitica is a free habit building and productivity application.
Simplified Twitter - The new Twitter, without distractions
HabitBull - HabitBull
Readme for iOS - A minimal Twitter reader w/ no ads. Take back your timeline.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.