OpenAPI / Swagger Validator & Converter Online

Validate OpenAPI 3.0, 3.1, 3.2 and Swagger 2.0 against the official schemas, lint common mistakes, list endpoints, YAML ↔ JSON, upgrade Swagger 2 to OAS 3.

Result

Press “Run” to see the result.

Send an API definition as spec (YAML or JSON text, or a JSON object), as a text body, or give its url. With action=validate (default) the document is checked against the official JSON Schema of its version published by the OpenAPI Initiative (Swagger 2.0, OpenAPI 3.0, 3.1 and 3.2, refreshed weekly) and errors are reduced to the useful ones: for oneOf alternatives only the variant you most likely meant is reported, with the JSON pointer of each problem.

A built-in linter adds what the schema cannot see: $ref that do not resolve, duplicate operationId, path parameters missing from parameters or not in the template, path parameters without required: true, equivalent paths (/a/{id} vs /a/{name}), undefined security schemes, operations without a 2xx response, GET with a request body, server URLs ending with a slash, unused components, and missing descriptions, tags, contact or licence (as info). stats counts paths, operations by method, schemas and servers.

action=endpoints lists every operation (method, path, operationId, summary, tags, parameters, request body content types, response codes, security); action=convert turns YAML into JSON and back (to); action=upgrade converts Swagger 2.0 into OpenAPI 3.0.3 (servers from host / basePath / schemes, requestBody from body and formData parameters, components, security flows, $ref rewriting, x-nullable) and validates the result. External $ref files are not fetched. Up to 10 MB.

Use this in your code

curl -X POST "https://apibox.io.vn/v1/openapi-tools" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"spec":"openapi: 3.0.3\ninfo:\n  title: Shop API\n  version: 1.0.0\npaths:\n  /orders/{id}:\n    get:\n      summary: Get an order\n      responses:\n        '\''200'\'':\n          description: The order\n"}'

const res = await fetch('https://apibox.io.vn/v1/openapi-tools', {
  method: 'POST',
  headers: {
    Authorization: 'Bearer YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "spec": "openapi: 3.0.3\ninfo:\n  title: Shop API\n  version: 1.0.0\npaths:\n  /orders/{id}:\n    get:\n      summary: Get an order\n      responses:\n        '200':\n          description: The order\n"
  }),
});
const data = await res.json();
console.log(data);

import requests

res = requests.post(
    "https://apibox.io.vn/v1/openapi-tools",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={"spec": "openapi: 3.0.3\ninfo:\n  title: Shop API\n  version: 1.0.0\npaths:\n  /orders/{id}:\n    get:\n      summary: Get an order\n      responses:\n        '200':\n          description: The order\n"},
    timeout=30,
)
print(res.json())

<?php
$ch = curl_init('https://apibox.io.vn/v1/openapi-tools');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_HTTPHEADER => ['Authorization: Bearer YOUR_API_KEY', 'Content-Type: application/json'],
    CURLOPT_POSTFIELDS => '{"spec":"openapi: 3.0.3\\ninfo:\\n  title: Shop API\\n  version: 1.0.0\\npaths:\\n  /orders/{id}:\\n    get:\\n      summary: Get an order\\n      responses:\\n        \'200\':\\n          description: The order\\n"}',
]);
$response = curl_exec($ch);
print_r(json_decode($response, true));

API documentation → Get a free API key

FAQ

Which versions are supported?

Swagger 2.0 and OpenAPI 3.0.x, 3.1.x and 3.2.x, each with its official JSON Schema from spec.openapis.org.

Are Schema Objects validated in 3.1?

The 3.1 / 3.2 schemas check the document structure; schemas inside it are checked for structure by the lint rules and $ref resolution, not against the full JSON Schema meta-schema.

Does it follow external $ref?

No. References to other files or URLs are listed as info and not fetched; local references (#/...) are all resolved and checked.