What is "blockly"

Blockly is a client-side JavaScript library for creating visual block programming editors. It is a project of Google and is open-source under the Apache 2.0 License. It runs in a web browser, and resembles Scratch.

Blockly uses blocks that link together to make writing code easier, and can generate JavaScript, Python, PHP or Dart code. It can also be customised to generate code in any computer language.