Freebase : A community-curated database of well-known people, places, and things
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
HTTP API design : This guide describes a set of HTTP+JSON API design practices, originally extracted from work on the Heroku Platform API.
npoint.io : JSON storage bins with schema validation
Flagr : Flagr is an open source Go service that delivers the right experience to the right entity and monitors the impact. It provides feature flags, experime...
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.