OpenAPIValidatoren

OpenAPIValidatoren are software tools and libraries that ensure APIs conform to an OpenAPI specification (OAS). They serve both during design and in operation: spec validators check the OpenAPI document for structural correctness and internal consistency, while runtime validators enforce that actual requests and responses comply with the defined schemas and constraints. They are commonly used in contract testing to verify that a service implements the contract described in the OpenAPI file.

The validators work by loading an OpenAPI document, typically in YAML or JSON, and, for runtime validation, by integrating with an API server, gateway, or testing framework. They verify that requests follow the specified path and method, that parameters exist and have the correct types and formats, and that the request bodies and responses adhere to the declared schemas. They can handle multiple content types and support features such as examples, default values, and required versus optional fields.

Key features include automatic JSON Schema validation, support for reusable components, precise error reporting, and configurable validation rules. Many tools also offer auxiliary capabilities such as mocking, request/response virtualization, linting, and integration with CI/CD pipelines to fail builds on contract violations.

OpenAPI validators are employed for API governance, regression testing, and automated testing workflows. Prominent implementations and ecosystems include Prism, a runtime validator and mock server; Spectral, a linting and style tool for OpenAPI documents; and language-specific libraries that plug into web frameworks to perform in-process validation.