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.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Habitica - Habitica is a free habit building and productivity application.
Voice Swap - Live voice changer & face filters for video selfies.
HabitBull - HabitBull
Voxer - Turn your phone into a Walkie Talkie. Don't waste time on phone calls and voicemails.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.