Several online tools allow you to convert ZIP files to SB3. Here's how:
If you zipped the folder containing the assets rather than the assets themselves, Scratch will fail to read it. Re-zip by selecting only the inner contents. convert zip to sb3
Change the file extension from .zip to .sb3 using the steps outlined in Method 1. On Windows (Using 7-Zip or WinRAR): Enter your asset folder and select all files ( Ctrl + A ). Several online tools allow you to convert ZIP files to SB3
There are several scenarios where a developer or student might need to pack a ZIP file back into an SB3 file: Change the file extension from
Highlight all individual items inside (the project.json file and all the asset files together). Right-click the highlighted cluster.
This process is usually necessary when you have manually modified a Scratch project's internal components—such as its project.json file or individual assets like sprites and sounds—and need to repackage them so they can be reopened in the Scratch editor . Conversion Methods 1. Manual Renaming (Recommended)
Before starting the conversion, it helps to understand what lives inside an .sb3 file. If you change the file extension of any Scratch 3.0 project from .sb3 to .zip and extract it, you will find a specific ecosystem of assets: