Since 2009, Square has led the way with paying for things with a credit card through your mobile phone. The company's card reader plugs into the headphone jack of iPhones and Android devices and allows businesses to accept credit card payments at a cost of 2.75 percent per swipe.
But for the consumers, the app Pay with Square allows you to purchase items without your wallet. When you arrive at a store you can "open a tab" on your phone with the app. When you're ready to make a purchase, you just have to tell the merchant to put it on your tab to complete the transaction. By opening a tab, your information is automatically sent to the register as a payment option. To charge you for a transaction, the merchant just has to touch your picture and name on the screen.