Card.io. iPhone & Android. Free app, $.15 per scan. Another mobile payment option besides Square and Google Wallet, Card.io works for both iPhone and Android devices. No need for separate devices, though - Card.io works by taking a picture of your credit card. The app reads the information and transmits for payment. While Card.io does “read” your data, it does not save card numbers or payment information. All server communication is protected with SSL encryption, and servers are hosted in secure facilities. No contracts, set up fees, or requirement that the app be tied to a certain merchant account or payment gateway. Sounds simple? It is. Card.io has released its SDK to developers to enable them to leverage this very cool and simple payment method. Smartphone as wallet? All signs point to yes.