MobilePay offers consumers a way to pay by credit or banking card without having your physical card on hand by linking it to an iPhone app that automatically authenticates with vendors to transfer payment. The service is going into closed beta today after operating in stealth mode for the past couple of months, it announced today at TechCrunch Disrupt in San Francisco.Vendors can partner with MobilePay and allow users to pay directly through the iPhone app, and they don’t have to implement any new hardware or technology to do it. MobilePay transmits an authentication signal through the cloud that would otherwise come from a bank after a credit card is swiped, which authorizes payment to the vendor.Users link banking and credit cards to their MobilePay accounts and can use the app at any of the stores partnered with the payment service. To pay, users simply type in the amount of money they owe the vendor — along with a tip or cash back — and hit the send button. MobilePay’s platform is preloaded from the credit cards that users link to their MobilePay accounts, and it sends the authentication signal to partnered vendors’ equipment to authorize payment.The platform also gives vendors a way to offer rewards to repeat customers in the way of discounts and cash back for passing a certain threshold of money spent at the store. MobilePay picks up 1 percent of each transaction as payment for the service. It also has access to GPS data for individual users, which means it can deliver targeted advertising for deals — another potential revenue source.The Aliso Viejo, Calif.-based company was launched in May earlier this year but has since operated in stealth mode. The 10-person company has raised $1,400 to date.