Instinctiv pulls data from the server for 2 things at the moment (though more features will be server dependent in the future).

1) Instinctiv shuffle. Using an encrypted connection Instinctiv anonymously uploads the names (and other metadata) of the songs you have on your device. The server then returns you a "mood map" which lets Instinctiv shuffle know which songs are related to which other songs, how and by how much. We also monitor which songs you play and skip and use that to personalize the shuffle. For every 1000 songs budget 50k of data up and 4k of data down. For every 10 songs listened to, budget 1k up.

2) Artwork fetching. This one's the one that'll kill you. We download missing cover art and each cover can be up to a couple hundred k per song...