I like the idea and it's not specific to web development. So many times in my career I've wanted to share a schema and data types of an application across languages that need to communicate with each other. For example, a C script that generates JSON data to be read in a Python notebook into the same data types.

I'm aware that serialization frameworks like protocol buffers do this, but they usually come with a whole lot of other baggage, dependencies, hit-or-miss language support, and clunky APIs. I want something more lightweight that allows me to start developing an application by developing its schema, without it being tied to a specific serialization framework or language implementation.