Using Zukan offline
Scanning, searching and your collection work without a signal. Prices, sync and the Market tab do not.
The catalogue lives on your phone, so scanning, searching and browsing your collection never need a signal. Offline, a banner says so, and the collection shows the saved prices with their dates.
What needs a connection: fetching a price for a newly scanned card, the nightly price refresh, sync to your account, the Market tab and signing in. Everything catches up when the phone is back online.