Snap!

Snap! is a free block-based educational graphical programming language and online community. Snap allows students to explore, create, and remix interactive animations, games, stories, and more, while learning about mathematical and computational ideas. The Snap! editor, and programs created in it, are web applications that run in the browser without requiring installation. It is built on top of Morphic.js, a Morphic GUI, written by Jens Mönig as 'middle layer' between Snap! itself and 'bare' JavaScript.