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Understanding API Drift

API Drift occurs when your API's implementation—the actual code—no longer matches its specification (the OpenAPI file).

The Problem​

As APIs evolve, developers might add fields, change data types, or modify status codes. If the documentation isn't updated simultaneously, client applications relying on that spec will break.

The Drift Solution​

Project Drift is a spec-first testing tool. It ensures alignment through three core mechanisms:

  1. Specification as Source of Truth: Tests are mapped directly to your OpenAPI endpoints.
  2. Deep Schema Validation: Drift automatically validates response bodies against the JSON schemas defined in your spec.
  3. Repeatable CI/CD Validation: By running Drift in your automation pipeline, you catch drift before it reaches production.