Learn BLOCKLY with Real Code Examples

Blockly is a library-not a standalone programming environment.

It provides visual block editors that can generate JavaScript, Python, Dart, Lua, or PHP.

Developers embed Blockly into their own applications.

Blocks snap together to form logic structures.

Ideal for teaching coding or building visual logic tools.

Block rendering engine

Code generation API

Custom toolbox and categories

Events and workspace listeners

Internationalization support

Blocks represent operations

Toolbox contains categories

Workspace is where blocks combine

Connections define logic flows

Code is generated from the block tree

toolbox.xml - defines available blocks

customBlocks.js - custom block logic

workspace.js - workspace injection code

generators/ - code generators

themes/ - custom visual themes

Setup workspace via JavaScript

Define toolbox and block categories

Drag blocks into workspace

Customize or extend block definitions

Export or run the generated code

Beginner: simple math and logic

Intermediate: loops, conditionals

Advanced: custom blocks and code gen

Expert: embedding Blockly in large apps

Enterprise: workflow editors and logic builders

Blockly vs Scratch: Blockly is a library; Scratch is an app.

Blockly vs MIT App Inventor: App Inventor builds mobile apps; Blockly is generic.

Blockly vs Node-RED: Node-RED is flow-based; Blockly is block-based.

Blockly vs FlutterFlow: FlutterFlow is commercial; Blockly is open-source.

Blockly vs Tynker: Tynker is a platform; Blockly powers many platforms.

2012 – Initial release by Google

2015 – Code generators expanded

2018 – Major rendering updates

2020 – Plugins and theming system

2023–2025 – Ongoing modernization and modularization

Toolbox: menu of blocks

Workspace: area for building logic

Generator: converts blocks to code

Block definition: shape + fields

Serialization: storing blocks as XML/JSON