Check OpenAPI schemas for backward compatibility
Endpoint paths are only part of an API contract. Schema changes inside requests and responses are often where subtle consumer breaks occur.
Track response properties
Removing a documented response property can break typed clients, mappings and UI code even when the endpoint and status code still exist.
Compare primitive types
Changing a string to a number, an object to an array or another incompatible type changes the value a consumer must parse.
Detect new requirements
A formerly optional request field becoming required means existing callers can begin receiving validation failures.
Report the exact location
Contract Guard identifies the affected operation or schema path so a developer can understand and resolve the compatibility problem quickly.
Protect every pull request automatically
Install the GitHub App, choose a repository and get a clear pass or fail status whenever its OpenAPI contract changes.
Frequently asked questions
Does it resolve schema references?
The comparison engine follows supported local OpenAPI schema structures while analysing operation inputs and responses.
Are request and response rules the same?
No. Compatibility direction matters: making an input stricter and making an output narrower are common breaking patterns.
Can I check a schema before installing?
Yes. Paste or upload the baseline and candidate specifications into the free browser checker.
Can teams share the results?
Yes. Teams workspaces provide shared installations, checks, roles and central billing.