I want to create a simple web app embedded in a Confluence page that can modify page attachments. I have my code in a html macro. The devil is in the details with the API calls, so I would like something like codepen, jsbin, or jsfiddle with live-updating interactive code. I am not allowed to whitelist CORS requests from any of the services I just mentioned (or any other "external" server).
What is the best way to achieve this interactive development environment so all AJAX calls come from my internal Confluence server and avoid CORS blockage?