Otherwise it looks good! If you add the above I will have a reason to stop looking!
Any other features you would like to see in the app?
There is another service that allows for scripting which I’m sure some people love, but I just need somewhere I can set the response.
tl;dr: configure responses to your 3rd party http dependencies, matching against header or body or url, and returning a custom response, including headers.
The best feature, I think, is that you can pass a header in that configures the response, so you can have tests that dynamically force response content/errors. That and allowing your integration tests to validate error paths and various states.