OpenAPI to JSON Converter

What Does This Tool Do?

Many OpenAPI documents are authored in YAML for readability, but some tools and libraries expect JSON. This tool parses a YAML (or already-JSON) OpenAPI document and outputs it as clean, formatted JSON.

Why Use This Tool?

Useful when a code generator, testing tool, or API gateway specifically requires a JSON OpenAPI file, but your source document is maintained in YAML.

How to Use the OpenAPI to JSON Converter

1. Paste your OpenAPI document (YAML or JSON).
2. Click Convert to see the formatted JSON output.
3. Copy the result.

Troubleshooting

A parsing error usually points to an indentation mistake or an unquoted special character in the YAML - check the line mentioned in the error message first.

Example

openapi: 3.0.3
info:
  title: Orders API
  version: 1.0.0
paths:
  /orders:
    get:
      summary: List orders
      responses:
        '200':
          description: OK

becomes:

{
  "openapi": "3.0.3",
  "info": {
    "title": "Orders API",
    "version": "1.0.0"
  },
  "paths": {
    "/orders": {
      "get": {
        "summary": "List orders",
        "responses": {
          "200": {
            "description": "OK"
          }
        }
      }
    }
  }
}

Why the Quotes on '200'?

In YAML, 200 without quotes is a number, but OpenAPI requires response codes as string keys. Quoting them in YAML keeps both formats correct - JSON keys are always strings anyway.

Where JSON Specs Are Needed

• Code generators and SDK builders that only read JSON.
• API gateways and cloud services that import a JSON definition.
• Scripts that read the spec with jq or JSON.parse.

Validate the document with the OpenAPI Validator, convert back with the OpenAPI to YAML Converter, and document endpoints in Markdown with the API Documentation Generator.