VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
Playlist Machinery - Tools that help you create & organize your Spotify playlists
PRIZM - Intelligent music player that you can plug into any speakers
Playlistor - Convert Apple Music playlists to Spotify and vice versa
Tycho Forecast - Turn your weather into a Spotify or Apple Music playlist
FreeYourMusic - Migrate from and to any music services