Beeceptor - Unblock yourself from API dependencies, and build & integrate with APIs fast. Beeceptor helps you build a mock Rest API in a few seconds.
WireMock - WireMock - a web service test double for all occasions.
Request inspector - Debug web hooks, http clients
Mockoon - Mock servers in seconds
RequestWatch - Inspect and debug HTTP requests
Mocko.dev - Proxy your API, choose which endpoints to mock in the cloud and inspect traffic, for free. Speed up your development and integrations tests.