“You can think of Mountebank as a small software appliance that is programmable via HTTP. The fact that it happens to be written in NodeJS is completely opaque to any calling service. When it launches, you send it commands telling it what port to stub on, what protocol to handle (currently TCP, HTTP, and HTTPS are supported, with more planned), and what responses it should send when requests are sent. It also supports setting expectations if you want to use it as a mock. You can add or remove these stub endpoints at will, making it possible for a single Mountebank instance to stub more than one downstream dependency.”