Appetize.io supports specifying a proxy server to route traffic, or you can use a tunneling tool like ngrok.io.
If you'd like the Appetize traffic to go through a proxy server, you can specify the proxy in a query parameter or by making use of our JavaScript SDK.
If you want your localhost available from Appetize, then you can also use a tool like ngrok.io to tunnel to your localhost. More info at http://ngrok.com.