Then you can visit "http://localhost:7878/first" in your browser to see it work. The quiet and port options can also be set in the config.json file, and values from config.json will override values from the command line. After you get up and running, you should put your config.json and mock responses in a better location. It's not a good idea to keep them under the "node_modules" directory. Make sure another process is not already using the port you want. If you want port 80, you may need to use "sudo" on Mac OSX. Sometimes you only want some service endpoints to be mocked, but have other requests forwarded to real service endpoints. In this case, provide the proxy URL option on startup e.g. apimocker --proxy http://myrealservice.io When the proxy option is set, any requests to apimocker with URLs that are not configured with mock files, will be forwarded to the specified URL.