mountebank : mountebank is the first open source tool to provide cross-platform, multi-protocol test doubles over the wire. Simply point your application under tes...
httpbin.org : A simple HTTP Request & Response Service.
Webhook Tester : Webhook Tester allows you to easily test webhooks and other types of HTTP requests.
Quicktype : Quicktype generates types and helper code for reading JSON in C#, Swift, JavaScript, Flow, Python, TypeScript, Go, Rust, Objective-C, Kotlin, C++ and ...
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.