YouTube Kids - YouTube for the youngins on iOS and Android
Circuito.io - Instant code and wiring for your project
Mashs and the Bear - Mashs and the Bear developed and published by 01Digital for Android and iOS devices.
library.io - Learn electronics and easily create circuit boards online
BabyFirst - BabyFirst: Education Songs, Games, and TV for Kids is a safe and fun way for kids to sprout, start learning, and explore.
B4R - Development tool for native Arduino programs.