JSON Schema to OpenAPI Converter
Paste an actual JSON Schema document to instantly generate a matching OpenAPI 3.0 components.schemas fragment, with nested objects extracted into named, referenced schemas. Free online developer tool.
Paste a JSON Schema document
OpenAPI Schema
OpenAPI components.schemas fragment will appear here...
Free JSON Schema to OpenAPI Converter
Paste an actual JSON Schema document — not a plain JSON data sample — to instantly generate a matching OpenAPI 3.0 components.schemas fragment. Nested objects are extracted into their own named schema and referenced with $ref, matching how OpenAPI documents typically structure reusable schemas.
How to Use It
Paste a draft-07-style JSON Schema object into the input box, or click "Load Example Schema" to see a sample run. The tool converts your schema's type/properties/required/items keywords, then emits an OpenAPIcomponents.schemas object with a named schema for the root and for every nested object, using OpenAPI's nullable: true sibling key instead of JSON Schema's type-array style for nullable fields.
Example
Given a schema with a nested address object, the tool generates aRoot schema whose address property is{ "$ref": "#/components/schemas/RootAddress" }, plus a separateRootAddress schema entry describing that object's own properties.
Common Use Cases
- Converting a standalone JSON Schema into a reusable OpenAPI component for an API spec.
- Migrating request/response validation schemas into an OpenAPI-documented API.
- Producing a first draft of an OpenAPI schema to paste into a larger
openapi.yamlfile. - Checking how a JSON Schema's nullable fields translate into OpenAPI's nullable convention.
FAQs
How does JSON Schema nullability map to OpenAPI?
JSON Schema commonly expresses "nullable" with a type array like ["string", "null"]. OpenAPI 3.0 doesn't support type arrays, so this converter instead adds a nullable: truesibling key next to the resolved type, which is the standard OpenAPI 3.0 convention.
Are $schema and $id kept in the output?
No — $schema and $id are JSON-Schema-specific metadata keywords that don't belong in an OpenAPI schema object, so they're dropped from the generatedcomponents.schemas fragment.
Is my schema uploaded anywhere?
No — parsing and schema generation happen entirely client-side in your browser. Nothing you paste is sent to a server.