US Patent 9037491 Card reader emulation for cardless transactions

Disclosed are method and apparatus that enable a cardless payment transaction to be executed from a merchant point-of-sale (POS) system. A user is enabled to check in at a merchant by using a mobile device of the user and then to pay by simply appearing at the merchant and mentioning his name. By emulating card read events and intercepting receipt printer outputs, the technique cleanly integrates into a conventional merchant POS system, without the need for customized software or hardware to accommodate individual POS vendor-proprietary application programming interfaces (APIs).