Get Blockly

There are several ways to get the Blockly code, and several ways to load it once you've gotten it.

Create-package script

Blockly provides a script that bootstraps a starter application, which you can then modify. It uses common web development tools like webpack and eslint, but doesn't include a framework, like React or Angular.

This requires you to install node.js and npm before running the following commands.

To create an application written in JavaScript in a new hello-world directory:

npx @blockly/create-package app hello-world

To create an application written in TypeScript in a new hello-world directory:

npx @blockly/create-package app hello-world --typescript

These create a package that imports package targets. It also uses a package.json file to manage dependencies, which makes it easy to stay up-to-date with the latest version of Blockly.

It also comes with some handy starter scripts, such as one to test the project locally in a browser:

cd hello-world
npm run start

You can refer to the generated package.json file for other commands.


If you are just playing around with ideas and don't want to bootstrap a full application, you can load Blockly from unpkg using script tags.

If you add the following to any HTML page, you can open the HTML directly in a browser to experiment with Blockly:

<!-- Load Blockly core -->
<script src=""></script>
<!-- Load the default blocks -->
<script src=""></script>
<!-- Load a generator -->
<script src=""></script>
<!-- Load a message file -->
<script src=""></script>

This is not a good long-term solution for acquiring Blockly, because it doesn't work with bundlers like webpack, but it is good for prototyping and experimentation.

Get the code

There are several ways which you can get the code to run Blockly.

The Blockly team recommends requiring Blockly through a package manager (like NPM or Yarn) because:

  • It is easier to stay up to date with changes in Blockly
  • It encourages using plugins instead of monkeypatching Blockly


npm install blockly --save


yarn add blockly


You can also download the compressed code from our GitHub releases. However, this requires you to manually download the code at regular intervals in order to receive the latest updates and fixes to Blockly.

Load the code

Once you've gotten the code, there are several ways you can access it from your code.

Script tags

<!-- Load Blockly core -->
<script src="./my-lib-directory/blockly/blockly_compressed.js"></script>
<!-- Load the default blocks -->
<script src="./my-lib-directory/blockly/blocks_compressed.js"></script>
<!-- Load a generator -->
<script src="./my-lib-directory/blockly/javascript_compressed.js"></script>
<!-- Load a message file -->
<script src="./my-lib-directory/blockly/msg/en.js"></script>

When using script tags, you can access imports from the global namespace:

// Access Blockly.

// Access the default blocks.

// Access the generator.


// Import Blockly core.
import * as Blockly from 'blockly/core';
// Import the default blocks.
import * as libraryBlocks from 'blockly/blocks';
// Import a generator.
import {javascriptGenerator} from 'blockly/javascript';
// Import a message file.
import * as En from 'blockly/msg/en';

When you import the message files, you also need to apply them.



// Require Blockly core.
const Blockly = require('blockly/core');
// Require the default blocks.
const libraryBlocks = require('blockly/blocks');
// Require a generator.
const {javascriptGenerator} =  require('blockly/javascript');
// Require a message file.
const En = require('blockly/msg/en');

When you require the message files, you also need to apply them.