Ampache

Ampache is a web-based media server that streams an audio or video collection over HTTP to browsers and connected devices. It organizes libraries into artists, albums, genres and playlists, serves tracks and clips through its own API and a Subsonic-compatible one, and can transcode on the fly to suit the connection a listener actually has.

People use it to reach a home music collection from anywhere, to run shared radio-style or on-demand streams, or to operate a listening server for a group of users.

Standing it up on your own server keeps your library private, avoids the per-user pricing of hosted plans, and means your files and database can be backed up and restored with tools you already know.