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.
UpEffect - Crowdfunding for social good products
Habitica - Habitica is a free habit building and productivity application.
Tickr - TICKR is GTK-based RSS READER application which displays RSS FEEDS in a TICKER bar on your desktop.
HabitBull - HabitBull
Creddon - Tweet for a cause and a sponsor will donate $1 to charity
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.