A formal agreement between data producers and consumers that specifies the structure, quality standards, update frequency, and terms of a data feed or dataset.
A data contract makes implicit expectations explicit. It defines what fields the data will contain, what data types they will use, what quality standards apply, how often the data will be updated, and what happens if the producer changes the data structure. Data contracts are increasingly used in data engineering to prevent breaking changes from disrupting downstream consumers.
Example: A city's transit authority provides a real-time vehicle location feed to third-party app developers. The data contract specifies: the feed will contain vehicle ID, route, latitude, longitude, and timestamp; latitude and longitude will always be present and valid; the feed will be updated every 30 seconds; and the producer will give 90 days' notice before changing the field structure. Developers can build reliable applications knowing the feed will behave as specified.