Mercure: Real-time Made Easy

Mercure is an open protocol for real-time communications designed to be fast, reliable and battery-efficient. It is a modern and convenient replacement for both the Websocket API and the higher-level libraries and services relying on it.

Mercure is especially useful to add streaming and asynchronous capabilities to REST and GraphQL APIs. Because it is a thin layer on top of HTTP and SSE , Mercure is natively supported by modern web browsers, mobile applications and IoT devices.

A free (as in beer, and as in speech) reference server as well as a hosted service are available.