Bliss.js : Want to use Vanilla JS but find native APIs a bit unwieldy? Bliss is for you
Cliquet : Cliquet is a toolkit to ease the implementation of HTTP microservices, such as data-driven REST APIs.
Motty : Motty provides the simpler way to test your client services.
It is a web application which gives you ability to create your own custom responses.
So y...
Collage.js : Collage.js brings together many public APIs, along a method of presenting media within a limitless two-dimesional space to create memorable experience...
Hoppscotch : A free, online, open source API request builder
Bluepine is a DSL for defining API Schema/Endpoint with the capabilities to generate Open API (v3) spec, validate API request and serialize object for API response based on single schema definition.