Images and sounds are stored at the top level. They are typically named by their MD5 checksum (e.g., 83a1...png ).
Numerous .svg , .png , or .wav files representing the project's sprites, backdrops, and audio tracks named as MD5 hashes.
Take the newly created .zip file and change its extension to .sb3 using the steps from Method 1. Method 3: Using Online Conversion Tools
def zip_to_sb3(zip_path, output_path=None): if not output_path: output_path = zip_path.replace('.zip', '.sb3')
Change the text at the end of the filename from .zip to .sb3 . convert zip to sb3
This usually happens if you zipped the parent folder instead of the individual files. Scratch expects project.json to be at the immediate root of the archive. Re-compress by selecting only the files inside the folder.
Because SB3 files are ZIP archives internally, —you simply change the file extension or repackage the contents. If you have a folder or a ZIP that contains the correct internal structure (a project.json file and asset folders), you can turn it into a working SB3 file in seconds.
# Check if it's a valid SB3 candidate with zipfile.ZipFile(zip_path, 'r') as z: if 'project.json' in z.namelist(): shutil.copy(zip_path, output_path) print(f"Converted: zip_path -> output_path") else: print(f"Invalid SB3 structure: zip_path")
The most common mistake is zipping the parent folder that contains the assets. Scratch cannot read the file if it is nested inside an extra folder layer. Images and sounds are stored at the top level
for file in os.listdir('.'): if file.endswith('.zip'): zip_to_sb3(file)
Sometimes manually inspecting the project.json is the only way to find why a project won't load. If you'd like, let me know: Did you manually edit the files inside the ZIP?
First, let’s look under the hood. When you save a project in Scratch 3.0, the software creates a file ending in .sb3 . But what is inside that file?
Open your web browser and navigate to the official Scratch Editor. In the top menu bar, click on . Select Load from your computer from the dropdown menu. Take the newly created
// Export to a ZIP archive, then save as an SB3 file const zip = await project.zip(); await Deno.writeFile("my-project.sb3", zip);
The file extension is the standard format for Scratch 3.0 projects. Structurally, an .sb3 file is actually a renamed ZIP archive containing the project’s assets (images and sounds) and a project.json file that defines the code.
Whether you're a seasoned Scratch user or just starting out, we hope this article has provided valuable insights and practical tips for converting ZIP files to SB3. Happy converting!