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.
Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
HabitBull - HabitBull
TeXworks - The TeXworks project is an effort to build a simple TeX front-end program (working environment)...
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
TeXstudio - TeXstudio is an integrated environment for writing LaTeX documents.