Specmatic

Specmatic turns API specifications into executable contracts. It continuously verifies that changes made by engineers or AI coding agents remain consistent with the specified behaviour, so that integration problems between services are found before integration.

The same specifications drive the whole API lifecycle: OpenAPI/Swagger, AsyncAPI, GraphQL SDL, gRPC proto files, Arazzo workflows and WSDL become contract tests run against a provider and intelligent mocks that stand in for dependencies. The Core component brings contract testing and mocking to developer workflows and CI/CD through the command line, Studio provides a visual workspace, and further components cover specification linting, design and governance.

Specmatic Core is open source under the MIT licence; Studio and the governance components are commercial.