Edge Side APIs (ESA) is an architecture pattern, that allows the creation of more reliable, more efficient, and less resource-intensive APIs. This architecture revives the main REST/HATEOAS principles while taking full advantage of the new capabilities provided by the web platform.

ESA promotes a mixed approach, synchronous and asynchronous, which allows a great simplicity of development and use, performances rarely reached, and the possibility for the clients to receive updates of the resource it fetched in real-time. Finally, ESA proposes to build on existing standards to expose documentation allowing the creation of generic clients, capable of discovering the capabilities of the API at runtime.