What are the top Erlang repos?

Popular Erlang repositories on GitHub, each answered in plain English for non-coders: what it is, its tech stack, and how to run it.

emqx/emqxAn MQTT message broker built to connect millions of IoT devices simultaneously, route their messages in real t
apache/couchdbA database that stores and syncs JSON documents over HTTP, letting multiple copies stay in sync across servers
d4l3k/cs418An Erlang-based repository named cs418 with no description, documentation, or feature list. It appears to be u