What is HATEOAS?

HATEOAS is the highest level of REST maturity (Richardson Maturity Model Level 3). API responses include hypermedia links telling clients what actions are available from the current state. For example, an order response might include links to cancel, update, or pay for the order. This makes APIs self-documenting and discoverable — clients follow links rather than constructing URLs. Benefits include decoupling clients from URL structure, enabling server-side URL changes without breaking clients, and guiding clients through valid state transitions. While theoretically elegant, many practical REST APIs skip HATEOAS in favor of documented URL patterns.