Sleep Cycle - Bio-alarm clock that wakes you up at optimal times based on your sleep patterns.
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
SleepBot - SleepBot is a sleep tracking app available in Google Play and the Apple App Store.
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.
Talalarmo - Minimalistic android alarm
Bubble.io - Building tech is slow and expensive. Bubble is the most powerful no-code platform for creating digital products.