Convert Zip To Sb3 ((free))
How to Convert a ZIP File to an SB3 File
If you have a folder full of Scratch assets (sprites, sounds, costumes, and JSON code) or a modified project archive, you may need to convert it into an SB3 file to upload it to the Scratch website or open it in the Scratch app.
The good news? An SB3 file is actually a standard ZIP archive with a different file extension. Here’s how to convert one to the other. convert zip to sb3
Q5: What about other Scratch mods like Snap! or GP?
Snap! uses XML, not SB3. This guide applies only to Scratch 3.0-compatible environments. How to Convert a ZIP File to an
Summary Table
| From | To | Method |
|------------|-------|-------------------------------|
| .zip | .sb3| Rename file extension |
| Unzipped folder | .sb3| Zip contents → rename to .sb3 | Summary Table | From | To | Method
Minimal checklist before packaging
- project.json present at archive root
- All assets referenced by project.json included
- Filenames and relative paths match references
- project.json is valid JSON
- Archive uses ZIP compression (standard deflate is fine)
1. Incorrect Internal Structure
Error: “Unable to load project” or infinite loading.
Fix: Ensure project.json is at the archive’s root, not inside a subfolder. Unzip, rearrange, and re-zip using Method 2.
Method 4: Command Line (For Developers and Batch Operations)
If you need to convert dozens of ZIPs to SB3, use a script.
Step-by-step: Convert safely (Windows, macOS, Linux)
- Create a working folder and copy the ZIP there.
- Extract the ZIP into the working folder.
- Locate project.json at the root of the extracted files. If it’s inside a single top-level folder, move its contents up so project.json is at the archive root.
- Verify assets referenced by project.json (image/sound filenames) are present and match exactly.
- On Windows:
- Select all files and folders (project.json + media folders).
- Right-click → Send to → Compressed (zipped) folder.
- Rename the resulting .zip to use the .sb3 extension (e.g., myproject.sb3).
- On macOS:
- Select all items, right-click → Compress.
- Rename the .zip to .sb3.
- On Linux (command line):
- From the working folder containing project.json, run:
(This creates myproject.sb3 in the parent directory.)zip -r ../myproject.sb3 *
- From the working folder containing project.json, run:
- Test by opening the .sb3 in Scratch (offline editor or upload to the Scratch website). If it fails, check project.json paths and asset names.
Method 3: Using Online Converters (Quick & Easy)
For non-technical users or when you’re in a hurry, several free online tools can “convert” ZIP to SB3.