API Contract - CI/CD Glossary Definition
An API contract is the machine-checkable agreement describing how a client and server exchange requests and responses.
An API contract is the agreed specification of how a client and server communicate: the endpoints, request and response shapes, status codes, and error formats. In CI, a contract test asserts that a running service still honors this agreement before deploy.
Contracts turn "the API should work" into something a pipeline can verify. Contract tests run in CI to catch a service drifting away from what its consumers expect, before that drift reaches production.
Why it matters in CI
A contract test in a workflow fails the build when a producer changes a response shape a consumer relies on, catching integration breaks before merge instead of in production.