This is a command line tool that uses libspotify (version 0.0.6) to sort all playlists and playlist folders in your Spotify library alphabetically.
Requires libspotify.framework to be installed, probably by copying it to /Library/Frameworks. See https://developer.spotify.com/en/libspotify/overview.
Tested on Mac OS X 10.6. Use XCode to build.
Please use with caution and keep backups.