Online JSON Schema to OpenAPI Converter
Migrating your data models between different standards can be a tedious manual task. Our JSON Schema to OpenAPI Converter automates this process, allowing you to transform standard JSON Schema definitions into OpenAPI Specification (OAS) compatible formats instantly. Whether you are building Swagger documentation or defining request/response bodies, this tool ensures accuracy and compliance.
Why Convert JSON Schema to OpenAPI?
While OpenAPI (formerly Swagger) uses a subset of JSON Schema, there are critical differences in how certain keywords like type, nullable, and format are handled between different versions (Draft 4, 7, or 2019-09) and the OpenAPI 3.0/3.1 specifications.
Bridging the Compatibility Gap
OpenAPI 3.0 has specific constraints that differ from standard JSON Schema. Our converter handles these nuances, such as converting dependencies to compatible logic or adjusting type arrays to meet OpenAPI's strict requirements, ensuring your API documentation remains valid.
Streamline API Development
Instead of rewriting your database models or validation schemas for your API docs, you can simply paste your existing JSON Schema. This reduces human error and keeps your backend logic and documentation perfectly in sync.
Key Features of Our Converter
Our tool is designed for developers who need precision and speed when managing API specifications.
1. Support for Multiple JSON Schema Drafts
Whether your source schema is based on Draft 4, 7, or 2020-12, our engine identifies the structure and maps it to the closest OpenAPI equivalent.
2. OpenAPI 3.0 & 3.1 Ready
OpenAPI 3.1 is now fully compatible with JSON Schema 2019-09. However, if you are still using OpenAPI 3.0, our tool will automatically "downgrade" specific fields (like nullable: true instead of type: ["string", "null"]) to maintain compatibility.
3. Instant Validation & Formatting
Not only does it convert the data, but it also beautifies the output. You get a clean, indented, and valid OpenAPI schema ready to be pasted into your components/schemas section.
How to Use the Converter
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Paste your Code: Copy your source JSON Schema into the input editor.
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Select Version (Optional): Choose whether you want the output to be optimized for OpenAPI 3.0 or the newer 3.1 standard.
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Click Convert: The tool will process the logic and display the OpenAPI-compliant result in the output window.
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Copy & Use: Use the "Copy" button to grab your new schema for your Swagger or Redocly documentation.
Technical Differences to Watch Out For
Handling the "Nullable" Property
In standard JSON Schema, a nullable field is often defined as type: ["string", "null"]. In OpenAPI 3.0, this must be converted to type: string with a separate nullable: true property. Our converter handles this automatically.
The "format" Keyword
OpenAPI uses the format keyword more extensively for validation (e.g., int32, int64, float, double). Our tool ensures that these formats are preserved and mapped correctly during the transformation.
Frequently Asked Questions (FAQ)
Is this converter compatible with Swagger 2.0?
While the focus is on OpenAPI 3.x, the generated schemas are largely compatible with Swagger 2.0, though some adjustments for the definitions section may be required.
Does my data leave my browser?
No. All conversion logic happens locally in your browser using JavaScript. Your sensitive API schemas are never sent to our servers.
Can I convert large, complex schemas?
Yes. Our tool is optimized to handle deeply nested schemas and large object definitions without performance lag.