Welcome to Kappa

Kappa is an OpenAPI library for the JVM. It supports contract-first API development, and can be used for

• Request validation
• Contract testing

Kappa provides first-class Spring Boot integration for both usecases. It also has adapters to work with other HTTP-related Java frameworks and libraries, like RestAssured, Vert.x and Undertow.

Version compatibility

Kappa targets providing complete support for OpenAPI 3.1. Currently it uses a draft2020-12 compliant validator for JSON Schema.

Relation to OpenAPI4j

Kappa is a permanent fork (successor) of the archived OpenAPI4J project. The first generally available version of Kappa is 2.0.0. Previous 1.x versions were released under the OpenAPI4j name.