: Ensure all project assets (e.g., .svg , .png , .wav files) and the mandatory project.json file are at the top level of your folder—not inside a subfolder.
If someone unzipped an .sb3 file, modified it, and gave you a folder, do this:
To extract the contents of an SB3 file:
| Method | Best For | Privacy & Security | Ease of Use | | :--- | :--- | :--- | :--- | | | Individual files, quick fix | ✅ Highest (your computer) | ⭐⭐⭐ | | Online Converters | On any device, no installs | 🔒 High (local browser) | ⭐⭐⭐⭐⭐ | | Manual Extraction | Troubleshooting file structure | ✅ Highest (your computer) | ⭐⭐ | convert zip to sb3 updated
Click the green button to download the converted file to your computer.
To avoid needing future ZIP-to-SB3 conversions:
Press and click Yes when Windows warns you about changing the extension. Open Finder and locate the ZIP file. : Ensure all project assets (e
Open the folder containing your project assets. You must see project.json right in front of you.
Describe it in the comments below (or on the Scratch Forums) and the community will help you debug it.
Here are the best ways to convert ZIP to SB3, updated for 2026: Open Finder and locate the ZIP file
If you are running into specific errors while uploading your file, let me know. I can help you figure out what went wrong if you tell me: What or device you are currently using?
So, an SB3 file is always a ZIP file at its core.