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DataToolings

JSON to OpenAPI Schema Converter

Convert JSON objects to OpenAPI 3.0 schema definitions. Generates component schemas with $ref references, required fields, and correct JSON Schema types.

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What Is a JSON to OpenAPI Schema Converter?

OpenAPI 3.0 (formerly Swagger) is the industry standard for describing REST APIs. Component schemas define the shape of request and response bodies. This tool reads any JSON object and generates a complete OpenAPI 3.0.3 document with components/schemas entries — including nested object references, arrays, and correct JSON Schema types.

How to Use

  1. Paste your JSON object into the left textarea.
  2. Set a root schema name, API title, and version.
  3. The OpenAPI document is generated automatically as you type.
  4. Copy the output and paste it into your OpenAPI spec file or Swagger editor.

Features

  • Generates a valid OpenAPI 3.0.3 document with components/schemas.
  • Nested objects become separate named schemas linked via $ref.
  • Arrays infer item type from the first element.
  • Non-null fields are listed in the required array automatically.
  • Numbers map to integer/int64 or number/double with format hints.
  • Runs entirely in your browser — no data is sent to any server.

FAQ

Can I use this output directly in Swagger UI?

Yes. The generated document is valid OpenAPI 3.0.3 JSON. You can paste it into Swagger Editor or serve it as your API spec. You will need to add your actual paths entries manually, as those depend on your API design.

How are nested objects handled?

Each nested object becomes a separate named schema under components/schemas, and the parent field references it with a $ref. This follows OpenAPI best practices for reusable schemas.

What is the difference between OpenAPI 2.0 (Swagger) and 3.0?

OpenAPI 3.0 replaced the top-level definitions key with components/schemas, added support for multiple servers, and improved request body handling. This tool generates 3.0.3, the most widely supported version.