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.
Mockoon - Mock servers in seconds
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.
Mockable - Quickly define some REST or SOAP endpoints and have them return json/xml (dummy) data.
QuickMocker - Online API Mocking Tool: API simulation, Mock API, API stubbing, fake API or fake web services, API for tests, forward server callbacks or webhook notifications to the localhost, proxy requests, requests restrictions, response templating etc.