openapi-drift

Does the service still do what the spec says?

What it does

An OpenAPI document is a promise about a service, and nothing keeps the two together. It quietly becomes a description of what the service used to do, and every consumer finds out one failed call at a time.

pip install openapi-drift
openapi-drift openapi.json
openapi-drift https://example.com/openapi.json --live

The check nobody else runs

A response schema behind a $ref is correct, valid, and useless to the tools that turn an operation into a function signature, because they do not dereference. A validator sees a schema; a converter sees an argument with no type. The document passes everything and cannot be used.

That is not hypothetical. It cost a week on a specification that passed every other check.

What it is not

Not a fuzzer — it calls what you documented rather than generating traffic hunting for crashes. Not a syntax validator — a perfectly well-formed document can be unreadable by a machine.

Only safe calls

--live calls parameterless GETs only. A path with a placeholder or a required parameter is skipped rather than guessed at, because a guessed value reports drift that is the checker's fault. Nothing is ever written.