OpenAPI & Swagger Validator

An OpenAPI (formerly Swagger) validator analyzes REST API contract specifications written in YAML or JSON against official OpenAPI Initiative standards. It performs syntax verification, structural schema parsing, broken reference ($ref) discovery, path parameter consistency checks, security scheme validation, and design linting to guarantee your API documentation and SDK generation tools function without errors.

• OpenAPI 3.1.x: The latest modern standard featuring 100% JSON Schema 2020-12 compatibility, polymorphic union types (type: ["string", "null"]), webhooks, and reusable component definitions.
• OpenAPI 3.0.x: Widely adopted standard with components.schemas, requestBody, server arrays, and granular parameter targets (path, query, header, cookie).
• Swagger 2.0: Legacy specification with swagger: "2.0", host, basePath, definitions, and securityDefinitions.

• Missing path parameter definition: If your path is /users/{userId}, an operation parameter with name: userId, in: path, and required: true must be explicitly defined.
• Using "in: body" in OpenAPI 3.x: In OpenAPI 3.0 and 3.1, request bodies are defined via the requestBody object with a content map, not as parameter objects with in: body.
• Broken $ref pointers: Verify that internal references like $ref: '#/components/schemas/User' match the exact capitalization and nesting path of the schema definition.
• Duplicate operationIds: Every operationId in the entire specification must be globally unique to ensure client SDK generators can create distinct method names.

All parsing, AST traversal, YAML decoding, and validation runs entirely inside your web browser using web-standard JavaScript. Your API schemas, authentication keys, and proprietary endpoints are never transmitted or stored on any remote server.