When using a local server to receive messages from Mergent, you need to expose your local development environment to the internet. To do this, we recommend installing ngrok. ngrok is free to use. After installing ngrok, you can expose your localhost by running ./ngrok http 3000 on the command line. 3000 is the port number your API server uses to listen for messages. You should see a response that looks something like this: 
$ Forwarding    http://3j4oq7db.ngrok.io -> 127.0.0.1:3000
Make a note of the *.ngrok.io URL and send it to Mergent as your Task/Schedule’s request URL.