From the site:

LitterBox is a static code analysis tool for detecting bugs in Scratch projects. Bugs in Scratch programs can spoil the fun and inhibit learning success. Many common bugs are the result of recurring patterns of bad code.

LitterBox provides checks for a collection of common bug patterns. Given a Scratch project ID or a file, LitterBox retrieves and parses the source code of the project, and reports all instances of bug patterns identified. LitterBox can also check for code smells and provide metrics about selected Scratch projects.

I think it's neat that someone worked on and made this available for kids just starting to learn how to code in MIT's great Scratch tool.

(Let me know if y'all don't think this belongs here...)