Apps with 'Sync iTunes Libraries' feature
Tixati is a peer-to-peer file sharing program that uses the popular BitTorrent protocol.
doubleTwist is a media management app that organizes and syncs the iTunes playlists, videos and photos on your Android phone.
Swinsian is a sophisticated music player for macOS with wide format support, folder watching, advanced tag editing and designed to be responsive even with the largest libraries.
Add and remove music, videos, playlists and artwork on your iPod. Backup all those tracks you just cant lose onto your computer. Import them automatically into your iTunes library.
DJ Mixer supports video mixing, automatic DJ mixing, one-click beat-matching, BPM counter, seamless looping, iTunes Library support, etc.
iSyncr lets you sync iTunes playlists with your Android phone.
Sync any Android smartphone with any PC or Mac.
The free version can sync up to 20 items.