Mockable - Quickly define some REST or SOAP endpoints and have them return json/xml (dummy) data.
Beeceptor - Unblock yourself from API dependencies, and build & integrate with APIs fast. Beeceptor helps you build a mock Rest API in a few seconds.
Postman - The Collaboration Platform for API Development
Webhook.site - Instantly generate a free, unique URL and email address to test, inspect, and automate (with a visual workflow editor and scripts) incoming HTTP requests and emails.
MockServer - Easy mocking of any system you integrate with via HTTP or HTTPS.
WireMock Cloud - Fast and simple API mocking in the cloud, powered by WireMock.