Extension

This article is about the feature in the editor. For a list of extension blocks, see Blocks § Extensions.
*This article or section documents the current version of Scratch (version 3.0). For this article in Scratch 2.0, see Extension (2.0).*

An **extension** is a category of blocks that can be added to the Block Palette and extends the scope of the Scratch editor. Extensions make it possible to connect Scratch projects with external hardware (such as LEGO WeDo or micro:bit), sources of information on the web (such as Google Translate and Amazon Text to Speech), or blocks allowing for more advanced functionality. They add a collection of command and reporter blocks that can be used to interact with a particular device or data source. When an extension is enabled, its blocks appear in a location with the same name as the extension.

## Adding Extensions

To add an extension, press the blue icon at the bottom-left of the screen under the block categories. This will open the Extensions Library, and one can choose an extension. The extension will then show up in the block categories.

## Removing Extensions

If an extension was added, but none of its blocks are used in the project, reloading the project will automatically remove the extension.

## Available Extensions

Main article: List of Extensions
11 extensions are available on Scratch 3.0. Three extensions simply add blocks that weren't in extensions in Scratch 2.0, two are web extensions, which connect Scratch to additional functions on the Internet, and six are hardware extensions, which connect Scratch to an external device.

* Music - playing musical notes
* Pen - drawing with the pen
* Video Sensing - detecting camera movement
* Text to Speech - outputting speech from inputted text
* Translate - translating text with Google Translate
* Makey Makey
* micro:bit
* LEGO MINDSTORMS EV3
* LEGO BOOST
* LEGO Education WeDo 2.0
* Go Direct Force & Acceleration

The following extensions are only available on the Raspberry Pi release of Scratch:

* Raspberry Pi GPIO
* Raspberry Pi Sense HAT
* Raspberry Pi Simple Electronics

## Writing Extensions

Some features allow one to write one's own extensions.

### JavaScript Extensions

This extension mechanism uses JavaScript to create the extensions. The documentation for creating this kind of extension for Scratch 3.0 can be found here.

## Distributing Extensions

An extension distribution strategy is still being worked out.[*citation needed*] The Scratch team will probably host a small library of "supported" extensions.[*citation needed*] Users will be able to browse and select extensions from this library from within the Scratch editor.[*citation needed*] Supported extensions would be checked for quality and safety by the Scratch Team.[*citation needed*] There likely are strict criteria for including an extension in the Scratch Team-supported extensions library, such as command set clarity and ease of use, size of the potential audience, widespread availability of any associated hardware, and a long-term commitment to support the extension.[*citation needed*]

Projects with experimental extensions cannot be shared on the Scratch website and will result in a pop-up message whenever a user tries to share a project with experimental extensions. Extension developers can share their extensions by distributing Scratch 2.0 project files (.sb2). Users can then use the "File > Upload from computer" command to import the project that uses the extension.

## ScratchX

Main article: ScratchX
ScratchX was a gallery of experimental extensions that one could try out on the ScratchX website. The website could be found here. There were multiple Scratch extensions on ScratchX. It was discontinued in Scratch 3.0, due to the extensions being supported in the main Scratch editor, but it remained available to use here until the discontinuation of Flash.

## Scratch Lab

Main article: Scratch Lab
Scratch Lab is a website made by the Scratch Team to test extensions that could possibly be added to Scratch 3.0. As of February 2022, 2 extensions are available. These are Animated Text and Face Sensing. Scratch Lab can be found here.

## See Also

* Adding Extensions via Developer Tools
* Developing Scratch Extensions (forum)
* Hardware that can Connect to Scratch
* How to Connect to the Physical World
* LEGO Education WeDo Robotics Kit
* Making ScratchX Extensions
* Remote Sensor Protocol in Scratch 1.4
* Scratch 1.4 Modifications
* Scratch Modification
* ScratchX
* Scratch Lab

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