Music library manager and MusicBrainz tagger (command-line and Web interface).
Modern Music Server and Streamer, compatible with Subsonic/Airsonic.
Personal music streaming server that works.
Audiobook and podcast server. It streams all audio formats, keeps and syncs progress across devices. Comes with open-source apps for Android and iOS.
Extensible music server. Offers a superset of the mpd API, as well as integration with 3rd party services like Spotify, SoundCloud etc.
Synchronous multiroom audio server.
Streaming audio server with Linux/macOS/Windows/Android clients.