Abstract: Split integrator model methods and systems for conducting a consumer purchase transaction. In an embodiment, a payment system receives a checkout request message comprising checkout request data from a mobile device application running on a consumer mobile device of a consumer, identifies a payload recipient based on the checkout request data, and then transmits a transaction payload to the payload recipient that includes at least a merchant identifier, payment card account details and a purchase transaction amount. The process also includes the payment system receiving a transaction authorization request from the payload recipient, and then transmitting the transaction authorization request for purchase transaction authorization processing to an issuer financial institution (FI) computer.