Zip To Sb3 Converter

For those who frequently work with Scratch projects and need more sophisticated conversion capabilities, several specialized tools exist.

How it works

All your costumes and sounds, usually named with long alphanumeric strings (MD5 hashes). How to Convert ZIP to SB3 (The Manual Method)

Change an .sb3 file’s extension to .zip , and you’ll see the truth: it’s a standard ZIP archive containing JSON files (project.json), SVG or bitmap costumes, sound files (WAV or MP3), and metadata. Zip To Sb3 Converter

Converting a ZIP file back to SB3 is not always successful. Here are the common pitfalls:

Developers using external text editors to write Scratch code (using experimental text-to-blocks compilers) need to zip their work and convert it to SB3 to test it on the official Scratch website.

If you prefer to have complete control over the process or need to convert files without an internet connection, manual conversion is straightforward once you understand the file structure. For those who frequently work with Scratch projects

A zip file is a compressed file format that allows multiple files to be packaged into a single file. Zip files are widely used for sharing and storing files, as they are easy to create and extract.

Scratch expects DEFLATE compression (standard ZIP). The converter repackages the folder, ensuring no extra MacOS metadata ( __MACOSX ) or hidden system files slip in—common causes of “Invalid project” errors.

A project.json file containing all the code, blocks, and variables. Converting a ZIP file back to SB3 is not always successful

Ensure your unzipped folder contains a valid project.json at the root level. All assets must be referenced correctly inside this JSON.

What Scratch displays when you try to load the file?