I'd like to write my own API type of thing using MODx as my CMS. I am wondering if there is a RESTful plugin/module, or whether MODx is RESTful out of the box.
This is a late response, but I am also interested in seeing more discussion and documentation regarding REST with MODX.
I'm not sure about plugins or modules.
For GET requests, one way would be to use a snippet in a resource (page) to handle the request and generate a response. It would probably handle POST. I don't know about other HTTP verbs.
I found a modRestServer class in the API. Not sure if it would be useful for creating your own RESTful service.