Mobile wallets Mobile wallets are available as apps for your smartphone, especially useful if you want to pay for something in bitcoin in a shop, or if you want to buy, sell or send while on the move. This is a very effective way to tell if something has been changed, and is how the blockchain can confirm that a transaction has not been tampered with. For instance, a mining card that one could purchase for a couple of thousand dollars would represent less than 0. Bitcoin image via Shutterstock.