: A text file containing all the code, variable data, blocks, and coordination logic for your Scratch project.
If you're not comfortable with file extraction and renaming, you can use online tools to convert zip to Sb3. There are several websites that offer this service, such as:
: 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 your ZIP file already contains the raw assets and a valid project.json file in its root directory, you do not need any special software to perform the conversion. Step 1: Verify the Internal Archive Structure
With the discontinuation of Flash and the complete migration to HTML5, the Scratch team has updated how the platform handles data. While .sb2 files are still importable, the standard is .sb3 . For archivists and developers creating tools to migrate content from other platforms (like Unity or Stencyl) into Scratch, generating a ZIP and converting it to SB3 is the only programmatic way to inject assets into the ecosystem without manually uploading them one by one. convert zip to sb3 updated
The issue is the file extension . Even though the internal structure is identical, your operating system has saved the file with a .zip extension instead of .sb3 . The Scratch editor (online or offline) is programmed to look specifically for the .sb3 extension. If it sees .zip , it refuses to load the project.
When a Scratch project is saved, the platform takes the project’s logic (stored in a JSON file named project.json ) and bundles it alongside all the assets—costumes, backdrops, and sounds. This collection is then zipped up and stamped with the .sb3 extension. This design choice was a significant update from the previous Scratch 2.0 ( .sb2 ) format, moving away from a binary structure to a web-friendly, standard-compliant archive.
If you have a collection of Scratch assets (like sprites, sounds, and a project.json file) inside a ZIP folder and want to turn it back into a playable Scratch project, follow these steps:
This occurs when the file structure inside the ZIP file has an extra root folder. Ensure the asset files are not nested inside a subfolder when you compress them. : A text file containing all the code,
A collection of .svg , .png , .wav , or .mp3 files. These represent the costumes, backdrops, and sounds used in the project, named using cryptographic hashes (MD5 checksums).
| Problem | Likely Cause | Solution | | :--- | :--- | :--- | | After renaming, Scratch says "Unable to load project" | The ZIP was never a Scratch project | Use an unarchiver to look inside. If you see EXE, PDF, or DOC files, it is not a Scratch project. | | Project loads but sounds are missing | The ZIP was compressed using an incompatible algorithm (e.g., LZMA instead of DEFLATE) | Re-zip the project using the standard "Store" or "Normal" compression level in WinRAR or 7-Zip. | | Images are corrupted | The ZIP contained non-standard asset filenames with special characters | Rename all image files to simple names (e.g., costume1.svg ) before re-zipping. | | File is too large (>50MB) | Scratch has a 50MB limit for online projects | Reduce asset sizes or convert sounds to MP3 before re-zipping. |
: Select Compress to ZIP file (or Send to > Compressed (zipped) folder ). Mac : Select Compress [X] Items . A new ZIP file will be generated inside that folder.
Right-click the file and select (or press Cmd + I ). Under the Name & Extension tab, change .zip to .sb3 . In modern operating systems, this triggers a warning
Navigate to the official Scratch MIT website and open the Project Editor.
ezyZip will process the archive directly in your browser. It will list all the internal files, including the core .sb3 file.
If you are on a Chromebook or a mobile device where file extension editing is difficult, you can use a browser-based tool.
– This sounds like you want to convert a ZIP file to an .sb3 file (Scratch 3 project format). If you have a ZIP file that contains a Scratch project (usually with a .json and assets folder), you can simply rename the .zip extension to .sb3 — because .sb3 files are actually ZIP archives internally.
Rename this newly created ZIP file's extension to .sb3 using the steps outlined in Method 1. Method 3: Using Online Conversion Tools
: A text file containing all the code, variable data, blocks, and coordination logic for your Scratch project.
If you're not comfortable with file extraction and renaming, you can use online tools to convert zip to Sb3. There are several websites that offer this service, such as:
: 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 your ZIP file already contains the raw assets and a valid project.json file in its root directory, you do not need any special software to perform the conversion. Step 1: Verify the Internal Archive Structure
With the discontinuation of Flash and the complete migration to HTML5, the Scratch team has updated how the platform handles data. While .sb2 files are still importable, the standard is .sb3 . For archivists and developers creating tools to migrate content from other platforms (like Unity or Stencyl) into Scratch, generating a ZIP and converting it to SB3 is the only programmatic way to inject assets into the ecosystem without manually uploading them one by one.
The issue is the file extension . Even though the internal structure is identical, your operating system has saved the file with a .zip extension instead of .sb3 . The Scratch editor (online or offline) is programmed to look specifically for the .sb3 extension. If it sees .zip , it refuses to load the project.
When a Scratch project is saved, the platform takes the project’s logic (stored in a JSON file named project.json ) and bundles it alongside all the assets—costumes, backdrops, and sounds. This collection is then zipped up and stamped with the .sb3 extension. This design choice was a significant update from the previous Scratch 2.0 ( .sb2 ) format, moving away from a binary structure to a web-friendly, standard-compliant archive.
If you have a collection of Scratch assets (like sprites, sounds, and a project.json file) inside a ZIP folder and want to turn it back into a playable Scratch project, follow these steps:
This occurs when the file structure inside the ZIP file has an extra root folder. Ensure the asset files are not nested inside a subfolder when you compress them.
A collection of .svg , .png , .wav , or .mp3 files. These represent the costumes, backdrops, and sounds used in the project, named using cryptographic hashes (MD5 checksums).
| Problem | Likely Cause | Solution | | :--- | :--- | :--- | | After renaming, Scratch says "Unable to load project" | The ZIP was never a Scratch project | Use an unarchiver to look inside. If you see EXE, PDF, or DOC files, it is not a Scratch project. | | Project loads but sounds are missing | The ZIP was compressed using an incompatible algorithm (e.g., LZMA instead of DEFLATE) | Re-zip the project using the standard "Store" or "Normal" compression level in WinRAR or 7-Zip. | | Images are corrupted | The ZIP contained non-standard asset filenames with special characters | Rename all image files to simple names (e.g., costume1.svg ) before re-zipping. | | File is too large (>50MB) | Scratch has a 50MB limit for online projects | Reduce asset sizes or convert sounds to MP3 before re-zipping. |
: Select Compress to ZIP file (or Send to > Compressed (zipped) folder ). Mac : Select Compress [X] Items . A new ZIP file will be generated inside that folder.
Right-click the file and select (or press Cmd + I ). Under the Name & Extension tab, change .zip to .sb3 .
Navigate to the official Scratch MIT website and open the Project Editor.
ezyZip will process the archive directly in your browser. It will list all the internal files, including the core .sb3 file.
If you are on a Chromebook or a mobile device where file extension editing is difficult, you can use a browser-based tool.
– This sounds like you want to convert a ZIP file to an .sb3 file (Scratch 3 project format). If you have a ZIP file that contains a Scratch project (usually with a .json and assets folder), you can simply rename the .zip extension to .sb3 — because .sb3 files are actually ZIP archives internally.
Rename this newly created ZIP file's extension to .sb3 using the steps outlined in Method 1. Method 3: Using Online Conversion Tools