Does anyone know if there are any tools/frameworks for building the functionality for step-by-step code tutorial websites (bonus if it has an interactive code editor where the user can see what they're doing reflected as they code). Or are these things custom made in-house?

A good example is O'Reilly Oriole: https://www.oreilly.com/learning/regex-golf-with-peter-norvig or CodeAcademy.