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OpenAPI Compatibility Checker

Compare two OpenAPI 3.x specifications locally and review potentially breaking API contract changes by operation and field path.

Paste or choose the original and revised OpenAPI 3.0, 3.1 or 3.2 files. Check the severity and affected field path, then download a Markdown or JSON report for review.

Compare two OpenAPI files before release. The specifications stay in this browser.

Paste JSON or YAML below, or choose a file.
Paste JSON or YAML below, or choose a file.

Each file: up to 2 MB and 1,000 operations. Supports OpenAPI 3.0, 3.1 and 3.2.

How to use

Review OpenAPI changes before releasing an API

Compare two OpenAPI 3.x specifications locally and review potentially breaking API contract changes by operation and field path.

Step by step

  1. Provide the source using: Original specification / Revised specification.
  2. Choose: Check compatibility. Inspect the result before copying, downloading or using it elsewhere.
  3. Paste or choose the original and revised OpenAPI 3.0, 3.1 or 3.2 files. Check the severity and affected field path, then download a Markdown or JSON report for review.

Choosing the settings

OptionWhat changes
Original specificationReferences within a specification file are followed. External file or URL references are not fetched and appear as review findings. Recursive schemas are compared at their first occurrence and marked for review.
Check compatibilityThe checker compares operations, parameters, request bodies, response codes and media types, plus common schema changes such as removed properties, newly required request properties, type changes and enum values. Findings include the affected operation and field path.

Example and expected result

If the revised GET /users/{id} response makes an optional `email` field required, the report flags the changed response contract. Local `$ref` references are followed; external references and complex schema composition are called out for manual review. This is not a full specification validator or a test of the running API.

If it is not working

  • The result is a static contract review, not a complete OpenAPI conformance validator, runtime API test or security audit. Server behavior, authorization logic and complex schema composition can require manual review. The report says which references or recursive structures were not fully checked.
  • If parsing fails, check JSON or YAML syntax before reviewing the API findings. Put needed local references in the same document. Unresolved external references and unsupported schema constructs require manual review; this tool does not fetch them or test a live server.

What changes are checked?

The checker compares operations, parameters, request bodies, response codes and media types, plus common schema changes such as removed properties, newly required request properties, type changes and enum values. Findings include the affected operation and field path.

How are references handled?

References within a specification file are followed. External file or URL references are not fetched and appear as review findings. Recursive schemas are compared at their first occurrence and marked for review.

What is outside this check?

The result is a static contract review, not a complete OpenAPI conformance validator, runtime API test or security audit. Server behavior, authorization logic and complex schema composition can require manual review. The report says which references or recursive structures were not fully checked.

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