ZeroServer.tools

OpenAPI Validator

Validate OpenAPI 3.x and Swagger 2.0 YAML/JSON specifications for common errors.

OpenAPI / Swagger YAML or JSON

openapi: "3.0.0"
info:
  title: Sample API
  version: "1.0.0"
  description: A sample API to demonstrate OpenAPI validation
paths:
  /users:
    get:
      summary: List users
      operationId: listUsers
      responses:
        "200":
          description: OK
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: "#/components/schemas/User"
  /users/{id}:
    get:
      summary: Get user by ID
      operationId: getUser
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: integer
      responses:
        "200":
          description: OK
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/User"
        "404":
          description: Not found
components:
  schemas:
    User:
      type: object
      required:
        - id
        - name
      properties:
        id:
          type: integer
        name:
          type: string
        email:
          type: string

Valid OpenAPI specification

OpenAPI Validator — check OpenAPI 3.x and Swagger 2.0 specs for errors

OpenAPI (formerly Swagger) is the industry standard for describing REST APIs. A valid spec requires an info object with title and version, a pathsmap where each path starts with "/", and operations that include a responses field. This validator parses both YAML and JSON formats, checks required fields, validates path syntax, ensures all $refreferences resolve to defined schemas in components/schemas, and flags missing operationId values that break code generation tools.

Private & free — this tool runs entirely in your browser.