FastAPI : FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints.
Strapi : Open source Node.js Headless CMS to easily build customisable APIs
DevDocs : DevDocs combines multiple API documentations in a fast, organized, and searchable interface.
htty : htty is a console application for interacting with web servers. It’s a fun way to explore web APIs and to learn the ins and outs of HTTP.
Web Audio Studio : Visualize and debug Web Audio graphs
Write Web Audio API code and instantly see the graph it creates.
Inspect signal flow, tweak parameters, and hear ...
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.