[amoshi]

Many sites support Paypal which means your payment data is safe

[xur17]

I really wish there was an open standard for something like this.

[ceejayoz]

There is. https://www.w3.org/TR/payment-request/

Supported everywhere except Firefox (where there's currently a flag to enable). https://developer.mozilla.org/en-US/docs/Web/API/Payment_Req...