Express OpenAPI Validator

express-oas-validator is an Express.js middleware library designed for validating API requests and responses against an OpenAPI Specification (OAS) definition. The library, currently at stable version 3.0.1, provides two core functionalities: `validateRequest` for incoming request validation (body, headers, path, query parameters) and `validateResponse` for outgoing response payload validation. It differentiates itself by offering both request and response validation within the same middleware, unlike some alternatives that focus solely on requests. The library's `init` function allows developers to create multiple validator instances for different OpenAPI definitions within a single application. Recent updates, including v3.0.1, have added full TypeScript support, enhancing developer experience. While the release cadence is not strictly regular, major versions have introduced significant improvements and new features.