Extension

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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).

The Extensions Library.

The button to add an extension in Scratch 3.0.

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 purple 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. In Scratch 2.0, it was possible to remove an extension by clicking where its name was in More Blocks, and then clicking "Remove extension blocks".

Available Extensions

11 extensions are available on the Extensions Library in Scratch 3.0. Three extensions had their own block categories (that were not an extension) in Scratch 2.0. Two extensions are web extensions, which connect Scratch to additional functions on the Internet. Six extensions are hardware extensions, which connect Scratch to an external device. There is also one hidden extension for testing purposes.

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
CoreEx — A hidden extension

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

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

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This article or section documents something not included in the current version of Scratch (3.0). It is only useful from a historical perspective.

An extension distribution strategy is still being worked out. 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. Supported extensions would be checked for quality and safety by the Scratch Team. 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.^[1]

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).^{[citation needed]} Users can then use the "File > Upload from computer" command to import the project that uses the extension.

ScratchX

This article or section documents something not included in the current version of Scratch (3.0). It is only useful from a historical perspective.

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^{[dead link]} 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 November 2023, 3 extensions, Animated Text, Video Sprites, and Face Sensing, are available. Scratch Lab can be found here.

References

↑ Media:ExtensionsDoc.HTTP-9-11.pdf

[1] Media:ExtensionsDoc.HTTP-9-11.pdf

[1]

v • d • e Block Categories
Main Block Categories	Motion Blocks • Looks Blocks • Sound Blocks • Events Blocks • Control Blocks • Sensing Blocks • Operators Blocks • Variables Blocks (List Blocks) • My Blocks
Extensions	Music Extension • Pen Extension • Video Sensing Extension • Text to Speech Extension • Translate Extension • Makey Makey Extension • micro:bit Extension • LEGO MINDSTORMS EV3 Extension • LEGO BOOST Extension • LEGO Education WeDo 2.0 Extension • Go Direct Force & Acceleration Extension
Raspberry Pi Extensions	Raspberry Pi GPIO Extension • Raspberry Pi Sense HAT Extension • Raspberry Pi Simple Electronics Extension
Former Extensions	Motor Blocks • LEGO WeDo 1.0 Extension • Community Blocks • PicoBoard Blocks

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