Inside a valid Scratch 3.0 project file, you will always find:

This works if the file is a true .sb3 mislabeled as .zip .

: Ensure your ZIP archive contains a file named project.json at its root, along with any necessary assets (like .svg , .png , or .wav files).

Often, a ZIP file containing a Scratch project already is an SB3 file, just with the wrong extension. Locate your .zip file. Right-click and choose . Change the extension from .zip to .sb3 .

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: Open the Scratch Editor , go to File > Load from your computer , and select your new .sb3 file. Troubleshooting & Tools

You may need to convert a ZIP file to SB3 if you have a Scratch project saved as a ZIP file and want to:

A dialog box will appear asking if you want to keep .zip or use .sb3 . Click . Method 2: Re-Zipping Assets (For Extracted Folders)

Search for a trusted online file converter or a Scratch-specific file utility. Upload your .zip file to the platform. Select as the target output format. Click Convert . Download the processed .sb3 file directly to your device.

: Go to the Scratch Editor , click File > Load from your computer , and select your new .sb3 file to ensure it opens correctly. Why this works

: Select Compress to ZIP file (or Send to > Compressed folder). Mac : Select Compress [Number] Items .

: Ensure the project.json file is at the root level of the ZIP archive. If it is hidden inside a sub-folder within the ZIP, Scratch cannot read it.

Once renamed, navigate to the Scratch MIT Editor, click > Load from your computer , and select your newly created .sb3 file. Method 2: Re-archiving Unzipped Scratch Assets

I notice you've sent two separate requests:

If you have a customized .zip archive containing your Scratch project assets and need to change it back into a functional Scratch file, this updated guide will show you exactly how to do it safely and efficiently. Understanding the Relationship Between ZIP and SB3

How to Convert ZIP to SB3 (Updated Guide) Scratch is one of the most popular platforms for learning how to code. Projects created in Scratch 3.0 are saved with an .sb3 file extension. However, you might sometimes download a Scratch project only to find it saved as a .zip file, or you might have unzipped a project to edit its assets and now need to bundle it back up.