OpenAPI validator

How it works

OpenAPI (formerly Swagger) describes an HTTP API: its paths, operations, parameters, bodies, responses and security. Docs, clients, servers and contract tests are generated from that file, so a mistake in the spec ends up as broken code or documentation that lies. This validator tells you whether your spec is valid and, if not, where and why.

Paste the spec as YAML or JSON. The version is detected automatically: OpenAPI 3.0, 3.1, 3.2 or Swagger 2.0. Validation runs as you type, and each problem shows its line, its location in the document (for example, paths › /orders › post › responses › 201) and a plain-language detail.

There are two kinds of checks. The structural check uses the official OpenAPI Initiative JSON Schema and finds missing required properties, misspelled names and disallowed values; for the schema’s alternatives it shows only the one that applies, not a wall of repeated errors. The extra checks cover what the schema cannot see: broken $refs, undeclared path parameters, duplicate operationIds, equivalent paths and undefined security schemes. Unused schemas show up as warnings.

Below you get a summary with the API title and version and the list of operations, handy for reviewing at a glance what the API exposes.

Nothing leaves your browser.

Examples

openapi: 3.1.0
info: { title: Orders API, version: 2.14.0 }
paths:
  /orders/{orderId}:
    get:
      responses:
        '200':
          descripton: The order

5  Error  The path uses {orderId}, but no in: path parameter declares it
          paths › /orders/{orderId} › get
7  Error  Missing required property “description”
          paths › /orders/{orderId} › get › responses › 200
7  Error  Property not allowed here: “descripton”
          paths › /orders/{orderId} › get › responses › 200

openapi: 3.0.3
info: { title: Payments, version: '1' }
paths:
  /payments:
    post:
      requestBody:
        $ref: '#/components/requestBodies/Payment'
      responses:
        '201': { description: Created }

6  Error  The reference #/components/requestBodies/Payment does not exist in the document
          paths › /payments › post › requestBody

Frequently asked questions