Blockly Junior
Blockly-Junior is version of Blockly for young children that have not learned to read yet (3-5 year-olds). It is similar to ScratchJr, which is a simpler version of Scratch.
Blockly
Google's Blockly is a web-based, visual programming editor. Users can drag blocks together to build programs. All code is free and open source.
The project page is https://developers.google.com/blockly/