Business analysis glossary
API Contract
What it is
An API contract is the agreed description of how an API behaves: its endpoints, accepted inputs, returned outputs, error responses and rules. Both the provider and the consumer build against it. It is often written in a standard format such as OpenAPI, but a clear table of endpoints, fields and responses can serve the same purpose.
Why it matters
With a clear contract, two teams can work in parallel and test independently. Changes to the contract are discussed openly instead of breaking another system unexpectedly. An analyst reviews the contract against the business requirements, to confirm that every needed field exists and that the error messages are meaningful to users.
Example
The contract for the Brightpath Logistics tracking API states that POST /parcels requires a destination and weight, returns 201 with the new parcel number, and returns 422 listing each invalid field. When the provider wants to add a field, the contract is updated and the consumer is told first, so nothing stops working unexpectedly.