Method and system for extending application programming interfaces

The current document discloses methods and systems for providing extensions to web-services APIs, including RESTful APIs, and to extend other types of interfaces that define client/server-based distributed computing systems. The disclosed methods and systems are facilitated by, and include, respectively, a link registry within one or more server computers, or that is accessible to the one or more server computers, that together provide a web service accessed through an API. The link registry stores link-registry entries, each of which specifies one or more links to be added to response messages associated with a particular resource. The link registry, like any resource, is associated with a set of verbs, or functions, that allow entries to be added to, and removed from, the link registry and that allow entries to be modified. The link registry can be used both by server-resident functionality as well as by functionality within external computers to extend an existing web service or API.