API Design

OpenAPI Response Schema Checker

Paste an OpenAPI response schema to check type definitions, required fields, nullable handling, and $ref format against OpenAPI 3.0 and 3.1 specifications.

No data is transmitted — everything runs locally

OpenAPI Response Schema Checker

The OpenAPI Response Schema Checker validates response schema objects against OpenAPI 3.0 and 3.1 specifications, checking types, nullable handling, $ref format, and required response codes.

• Validate a response schema before adding it to an OpenAPI specification

• Check nullable field syntax for OpenAPI 3.0 vs 3.1 compatibility

• Detect missing required response codes in an API endpoint definition

• Verify $ref format before generating client code from the schema

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What does this tool tell you?
The OpenAPI Response Schema Checker validates response schema objects against OpenAPI 3.0 and 3.1 specifications, checking types, nullable handling, $ref format, and required response codes.
What affects the result most?
Validates OpenAPI 3.x response schema objects: type, properties, required, items, $ref. Missing required response codes: 200, 4xx (at least 400, 401, 403), 500 should be declared. additionalProperties: false enforcement — catches undeclared fields in API contract.
How should I use the result?
Treat the tool's output as a first-pass check, not a proof of correctness. A clean pass means no issues in the patterns this tool recognizes; a failure points to a specific problem you can investigate in your source. The underlying spec is the authoritative source for edge cases.
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