Blockly | Google Developers
"Blockly is a library for building visual programming editors."
- "Web-based, no Flash.
- 100% client-side.
- Only 150 KB compressed.
- Chrome, Firefox, Safari, Opera, IE.
- Android and iOS support.
- Variables, functions, arrays...
- Syntax errors are impossible.
- Basic type checking.
- Extend with custom blocks.
- Open source.
- Export as JS, Python, and more.
- Clean code generation.
- Execute code step-by-step.
- Translated to 40+ languages.
- RTL for Arabic and Hebrew."