ReqRes - A hosted REST-API ready to respond to your AJAX requests.
Greenboard - Generate beautiful static api documentation
JSON Placeholder - JSON Placeholder is a modern platform that provides you online REST API, which you can instantly use whenever you need any fake data.
Cleora - Native HTTP & WebSocket Client for iOS, iPadOS & macOS
JSON Server - Get a full fake REST API with zero coding in less than 30 seconds. For front-end developers who need a quick back-end for prototyping and mocking
JsonAPI - Application and Data, Languages & Frameworks, and Query Languages