What counts as a breaking API change?

A breaking change is one that can break existing clients: removing a path, operation, or response; adding a required parameter; making a parameter or request body required; changing a type; or removing an enum value. This tool flags those as breaking, with less severe changes marked risky, safe, or doc-only.

Can I paste YAML specs, not just JSON?

Yes. Paste either JSON or YAML for each spec. The tool parses JSON first and falls back to YAML, so OpenAPI and Swagger files in either format work.

Are my specs uploaded anywhere?

No. Both specs are parsed and compared entirely in your browser. Nothing is sent to any server.

OpenAPI Breaking Change Analyzer

API & Web

Compare two OpenAPI or Swagger specs and see exactly what changed — classified breaking, risky, safe, or doc-only — in your browser.

Paste the old and new spec (JSON or YAML).
Get a severity-classified change report with an exportable summary.
Covers paths, operations, parameters, request bodies, responses & schemas.

Runs locally

Specs to compare

Old spec (baseline) New spec (candidate)

Change report

Paste both specs to compare.

Scope: paths, operations, parameters, request-body requiredness, response status codes, and component schema properties/types/enums (refs resolved). Deep allOf/oneOf composition is summarized, not fully merged. Schema changes are classified conservatively.

Next steps

Open OpenAPI Client Snippets Open OpenAPI → Postman Open JSON Schema Validator

After reviewing breaking changes, regenerate clients or test collections from the new spec.

OpenAPI Breaking Change Analyzer

Specs to compare

Change report

Next steps

How to use the OpenAPI Breaking Change Analyzer

What it does

When to use it

How to use it

Tips & pitfalls

FAQ

Related guides