WireMock (nuget): In integraction test you can mock your external apis with test server. When you create instance of WireMock, It will as you mapping path and port number. For mapping path you neet to give __admin/mappings location in your local system and port you can give any number or else system will take 9966 port number.
Keywords: https://github.com/WireMock-Net|http://wiremock.org|wiremock