socmoth, CrazedGeek, and tbgvi are right that this is considered a CNP transaction and rates are higher. However, our focus is on mobile developers, not retail merchants. By taking friction out of the mobile checkout flow for those developers (because customers don't have to type out their cc number), conversions are higher, and thus revenues are higher.
Regarding the user experience: folks are used to scanning barcodes with RedLaser, business cards with CardMunch, and checks with PayPal and the Chase mobile app. If we can make credit card purchasing easy and fast on the phone, that's a good user experience.
Thanks for the feedback!
I can see the title on HN: "Card.io - fast and easy workouts"
Anything that increases conversions is great! Best of luck! I look forward to seeing it in the wild. In fact, are there any merchants in SF I can watch use it yet?
Doesn't seem that card.io is trying to get merchants to use this as a Square replacement at this point.
Of course, I'm not sure how this is useful, since I understand that in-app purchases need to be tied to the App Store account, but it might be more useful for Android.