Local browser tool JSON + YAML
See what an API change could break.
Compare Swagger 2.0 or OpenAPI 3.0/3.1 descriptions from the perspective of an existing API consumer.
BaselineThe contract clients already use
CandidateThe proposed replacement
A compatibility report will appear here.
Paste or open two specifications, or load the built-in example. Files remain inside this browser tab.
A useful signal, not a proof
Contracts have context.
The checker has limits.
The report focuses on existing API consumers and covers paths, methods, parameters, request bodies, responses, schemas, enum changes, and security requirements. Internal JSON Pointer references are resolved.
External references are reported but not fetched. Runtime behavior, custom validators, undocumented compatibility, callbacks, links, and semantic meaning still require human review.