Ably is a provider of real-time data delivery solutions that support the creation, delivery, and management of complex projects. The Ably API facilitates communication between the Ably service and a variety of client and server devices. The RESTful API is designed for use in servers that form part of the back-end of any given application, like a web application, that implement messaging concepts. The functional scope of the Ably REST API spans the authentication, message publication and message history retrieval as well as presence state and presence retrieval and application usage data retrieval. The API returns responses in mainly JSON format, although JSONP and HTML formats are also acceptable.