This level indicates that the API uses protocol properties (namely, HTTP verbs) to define the nature of the API. Thus GET is used for a read, POST is used to create a new resource, PUT to update a resource, and DELETE to of course delete the resource. The API also uses standard responses code such as 200 (OK) and 202 (ACCEPTED) to describe the result of the request.

Generally, most REST API implementations are at this level.