Hoppscotch : A free, online, open source API request builder
JSON API : A specification for building APIs in JSON. Clients built around JSON API are able to take advantage of its features around efficiently caching respons...
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...
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.