Camarero is a ready-to-use solution to add some JSON API functionality to the existing application or to implement the read-only JSON API from the scratch when more sophisticated (read: heavy) solutions are not desirable. Below is the typical picture of how Camarero is supposed to be plugged in.

It is blazingly fast.

https://dev.to/mudasobwa/plug-in-json-api-readonly-webserver-17b4