airtunes2mqtt
This is a little daemon that can retrieve an audio stream via TCP socket or from a Alsa Loopback device and stream it to Airplay/Airtunes compatible receivers. Via Web UI or MQTT you can control the receivers volume and enable/disable the receivers.
node-airtunes2
an AirTunes v2 implementation: stream wirelessly to audio devices.
rudeplay
Yet another node.js airplay server