Jukebox - Collaborative music player
Playlist Machinery - Tools that help you create & organize your Spotify playlists
OutLoud Social Jukebox - Control the music with your friends in real-time
Playlistor - Convert Apple Music playlists to Spotify and vice versa
Festify - Festify is a free Spotify-powered app that lets your guests choose which music should be played...
FreeYourMusic - Migrate from and to any music services