Scratch 2.0 File Format
The Scratch 2.0 File Format saves projects in version 2.0 of the Scratch programming language. Scratch is a language designed to teach programming to young children. Since the program code consists of graphical tiles rather than text-based source code, a binary format was used for the earlier Scratch 1.4 File Format, but the format has changed with 2.0. Scratch 2.0 runs from a web browser, so no installation is needed as with the earlier versions. Registered users can save their programs on the server, but unregistered users can still run Scratch online and upload/download programs saved on their own computer.
Scratch projects are stored in files with a .sb2 extension. The contents are ZIP-compressed data, including various items which are part of the project (.png, .svg, and .wav files, named with numbers). The main item is a file called project.json, in JSON format.
Detailed documentation can be found in the Scratch wiki.