What are some alternatives?
When comparing AppyBuilder and MIT App Inventor, you can also consider the following products
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Codefreebnb - Airbnb clone. Written with not one line of code
Kodular - Much more than a modern app creator without coding
Android Studio - Android development environment based on IntelliJ IDEA
AppsGeyser - Appsgeyser is the easiest to use DIY native mobile app creation platform.
appenguin - Turn the most complex web application or website to into an Android app in minutes, for free!