Subsonic - Subsonic is a free, web-based media streamer, providing ubiquitous access to your music and video.
AudioRelay - Listen to your PC audio, use your phone as a mic or stream audio from your phone
netjukebox - netjukebox is a web-based media jukebox for MPD, VideoLAN and Winamp/httpQ.
Airfoil - This software is from the Rogue Amoeba company, built to run on Mac and Windows platforms. It’s an audio-based software that allows the computers sound to play over a network device. Read more about Airfoil.
YouTube Music - YouTube Music is a streaming app primarily designed for Android and iOS mobile devices. The app lets individuals search for music from their favorite artists, enjoy playlists, and access 30 million musical tracks.
Porthole - Play all audio from your Mac through multiple AirPlay speakers at the same time. iOS 11 and macOS 10. 13 High Sierra both add multi-room AirPlay support to the operating sytem, making Porthole redundant.