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.
Greenify - Greenify is a mobile app that gives you greater control over your Android device's power usage, allowing you to get a lot more mileage out of your battery life without having to constantly plug it back into a charger.
HabitBull - HabitBull
Accubattery - Monitor's battery capacity through the use of science
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Power Battery - Power Battery, as the most professional battery saver app, could get up about 60% more battery life for Android phones or tablets.