Swagger : Swagger is a powerful open source framework backed by a large ecosystem of tools that helps you design, build, document, and consume your RESTful APIs...
Wit : Natural Language Interface for apps and devices. Build bots easily. You tell us what your user said, we tell you what your bot should do next. Your us...
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...
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
pump.io : Social server with an ActivityStreams API. It's a stream server that does most of what people really want from a social network.
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.