The best alternatives to Harmonize are Poolsuite, Lofi Club, and Harmony. If these 3 options don't work for you, we've listed a few more alternatives below.
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Lofi Club is a place for listening to live 24/7 Lofi music. Comes with more than 17+ tracks, Live Chat, Distraction-free music player, to-do list, Pomodoro timer, keyboard control, playlist, fullscreen mode makes the app super productive for daily use!
NepTunes is a desktop accessory that allows you to see and control your music (Apple Music, Spotify) with customizable shortcuts, built-in scrobbler for Last.fm, and beautiful widgets.