OpenAPI 3.x contract checks

Catch breaking API changes before your customers do.

Compare two OpenAPI specifications in your browser. Get a clear, downloadable report of removed endpoints, new required inputs and incompatible schemas.

Check my API — freeNo account. No upload. Your specs stay in your browser.
✓ JSON & YAML✓ Runs locally✓ Downloadable report✓ No signup
01

Compare your contracts

Use a production specification as the baseline and the proposed version as the candidate.

Your files never leave this device.
02

Built for the pull-request loop

The web checker is free. Automated repository checks are the paid product.

1

Compare

Parse OpenAPI JSON or YAML and map endpoints, parameters, request bodies, responses and schemas.

2

Explain

Turn a noisy structural diff into a prioritised list your team can act on immediately.

3

Block

Pro will run on every pull request and fail the check when a breaking change is introduced.

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Contract Guard Pro

Automatic GitHub pull-request checks for private repositories.

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