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.
iBucket - A social bucket list apps that helps you achieve your goals & trips. Available for iOS, Android and Web. Dream it. Plan it. Do it.
Habitica - Habitica is a free habit building and productivity application.
Kurator - The premier Chrome extension for savvy researchers and publishers alike. Curate your interest and publish to your website, newsletter and social media sites directly from the browser.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
FocusOKR - Focus and achieve your goals using Objectives and Key Results
HabitBull - HabitBull