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.
Day One - A simple journal application for the Mac, iPhone, and iPad. AboutTo learn more about Day One, see these two excellent reviews . PublishPublish is not available in Day One 2.
HabitBull - HabitBull
Journey - A diary that keeps your private memories forever.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Diaro - Multiplatform online diary and mobile app designed to record your activities, experiences, thoughts and ideas. Join now for free and keep your secret diary or diet, travel or life journal securely.