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.
paste.ulvis.net - Add paste
Habitica - Habitica is a free habit building and productivity application.
JustPaste.it - Want to share text with your friends? Paste it below and give them a link.
HabitBull - HabitBull
Pastebin.com - Pastebin.com is a website where you can store text for a certain period of time.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.