My take: RecipeUI a Postman-like tool that offers convenient type safety and autocomplete on top of what Postman already does.

What is Postman? It's a tool that allows you to configure, save, and replay HTTP requests. It helps developers building backend server APIs, so they don't have to keep fiddling around with their frontend. In many greenfield projects, the frontend doesn't even exist yet and Postman is effectively the only way to easily test what you're working on.

The alternative to postman is writing custom Python/NodeJS/etc programs to send these requests or painfully doing it with curl and bash.

I think it's cool and I'll probably try it the next time I have to work on REST APIs.