Phoenix is a web development framework written in the functional programming language Elixir.

[2] Based on the Plug library,[3] and ultimately the Erlang HTTP server Cowboy,[4] it was developed to provide highly performant and scalable web applications.

In addition to the request/response functionality provided by the underlying Cowboy server,[5] Phoenix provides soft realtime communication to external clients through WebSockets or long polling using its language agnostic channels feature.

LiveView provides real-time user experiences with server-rendered HTML over HTTP and WebSocket.

[8] HEEx is Phoenix's templating language which provides HTML-aware compile time checking.