Click the green Save button next to the .sb3 file to download it to your selected destination folder on your device.
Scratch identifies assets by their exact MD5 filenames inside the archive. If you renamed an asset file manually without updating its corresponding reference ID inside the project.json file, Scratch will skip loading that asset.
Sometimes ZIP files converted back to SB3 don't open because the compression format is wrong or the project.json is corrupted. How it works:
Since the .sb3 format is just a zip file in disguise, you can often bypass conversion tools entirely by renaming the file extension. Find the .zip file on your computer. Rename the file:
ezyZip provides a secure, locally-processed tool that doesn't require uploading files to a server, making it ideal for large projects or privacy-focused users. Go to the ezyZip converter page. convert zip to sb3 updated
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
Scratch 3.0 expects the project.json file to be at the root of the ZIP archive, not inside an extra folder. By selecting the internal files directly, you recreate the correct internal structure.
: Change the file extension from .zip to .sb3 . In modern operating systems, this triggers a warning about file stability, which can be safely ignored in this context. Modern Web-Based Converters
If you see project.json , the conversion succeeded. Click the green Save button next to the
A warning prompt will ask if you are sure you want to change the extension. Click . Open Finder and locate the ZIP file.
In 2026, a growing number of educators use AI assistants (like ChatGPT with coding plugins or specialized Scratch AI tools) to generate .sb3 files. These AIs sometimes output a .zip archive containing the project.json and assets because web APIs handle ZIPs more easily than binary file transfers.
Because of this architecture, converting a ZIP to an SB3 often requires proper file structuring rather than a complex file format translation. Method 1: The Manual Extension Rename (Fastest Method)
: If you manually edited the code text, a missing comma, bracket, or quotation mark will corrupt the file. Use a free online JSON validator to ensure your syntax is correct before compressing. Sometimes ZIP files converted back to SB3 don't
: For the conversion to work, the ZIP file must contain the project assets directly in the root (e.g., project.json and various .svg or .wav files). If these files are inside a subfolder within the ZIP, Scratch will not be able to open it.
Note: Always ensure you trust the online tool before uploading files, especially if the project contains personal assets or custom audio recordings. Troubleshooting Common Errors
for each if one is missing, and exports a batch of SB3 files.
⚠️ Do not double-extract the file. If you already unzipped it into a folder, you must re-zip the contents correctly (see Method 3).