A ZIP file is a container—an SB3 is a specification. Respect the internal structure, preserve asset integrity, and always test. That’s the difference between a file that “kind of works” and one that delivers the full Scratch experience.
If you have a collection of Scratch assets and a project.json file that you want to bundle back into a functional project, follow these steps to maintain high quality: zip to sb3 extra quality
An .sb3 file is the native file format for . Internally, it is a collection of: project.json : The code and logic of your project. SVG/PNG files : The costumes and backdrops. WAV/MP3 files : The sound effects and music. A ZIP file is a container—an SB3 is a specification
Ensure all project files (e.g., project.json , .svg costumes, .wav sounds) are directly inside a single folder. Do have them nested inside a sub-folder within the ZIP. Compress the Files If you have a collection of Scratch assets and a project
To convert a file to an (Scratch 3.0) format, you essentially need to re-package extracted Scratch assets into a compressed folder and manually change the file extension. How to Convert ZIP to SB3 file is technically a renamed
: For the file to function as a Scratch project, it must contain a project.json file at the root of the archive.