Does this tool support OpenAPI 2.0 (Swagger)?

No, this validator specifically requires OpenAPI 3.x specifications to resolve response schemas accurately.

Can I validate YAML and JSON specifications?

Yes, the tool accepts both YAML and JSON formats. You can set the format manually or leave it on 'Auto' for automatic detection.

What does 'Disallow Additional Properties' do?

It enforces strict validation by throwing warnings if the response JSON contains fields that are not documented in the OpenAPI schema.

How do I format the path input?

Enter the actual request path, such as /users/123. The tool will match it against the templated paths in your OpenAPI specification.

Can I validate error responses?

Yes, simply enter the corresponding error status code (like 400 or 404) to validate the payload against that specific error schema.

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API Response Contract Validator

Validate a real API response JSON against the response schema declared in an OpenAPI 3.x specification

Details

What this tool helps you do

Paste an OpenAPI 3.x document plus one actual API response payload, then point the validator at the path, method, and status code you want to check. The tool resolves the matching response schema and highlights missing fields, type mismatches, enum problems, and undocumented fields.

How to use it:

OpenAPI Spec: paste YAML or JSON spec content
Response JSON: paste the actual runtime response payload
Path / Method / Status Code: identify the operation and response branch to validate
Spec Format: leave auto unless you know the spec format already
Disallow Additional Properties: raise warnings for payload fields that are not documented in the schema

Execution

Run this tool

Fill in the form, run the tool, and review the result in one place.

Prepared example runs

Click an example to fill the form automatically. File inputs still need an upload.

1 examples

Check whether a production response still matches the documented user schema

Validate a real JSON response against the OpenAPI contract and surface missing or extra fields before the frontend breaks.

<div>Contract validation issues</div>

Inputs

Set the required fields, then run the tool.

7 options

ContentPaste or type the main input values.4

OpenAPI SpectextareaRequiredResponse JSONtextareaRequiredPathtextRequiredStatus CodetextRequired

SettingsAdjust formats, ranges, numbers, and modes.2

MethodselectOptionalSpec FormatselectOptional

TogglesEnable or disable optional behavior.1

Disallow Additional PropertiescheckboxOptionalEnabled when checked

Result

Ready for a run

Run the tool to preview files, text, structured data, or streamed output here.

Samples

API Response Contract Validator

What this tool helps you do

Run this tool

Prepared example runs

Inputs

Result

Examples that match this tool

Continue with connected tools and hubs

Prepared example runs

Inputs

Result

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Validating a GET User Response

2. Detecting Undocumented Fields in Production

FAQ

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