MIT App Inventor is a block-coding tool with which you can create downloadable Android applications as .apk files, FOR FREE!
Python-driven web application tool. Looks great.
Fabulous tool to create mobile and desktop apps, like Powerpoint but with code.
A gallery of great apps and games made with MIT App Inventor, and the best thing is, you can look at the code to see how they did it, or remix an app to make your own version.
Nice list of the sorts of apps you can make with the block-coding (like Scratch) tool, Thunkable.
The 2019 list of apps made with Thunkable you can go and download from your App Store.