The best alternatives to Playlist Sorter are Playlist Machinery, SpotifyEditor, and Muru Music. If these 3 options don't work for you, we've listed a few more alternatives below.
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Haggle — A CTA buyers want to click, when they aren't ready to demo
Backtube is a playlist app where you can request recommendations through themes and create your own playlists and link them to other themes. You can listen to the playlists on the app and search and listen to Youtube and Bandcamp music catalog as well.