Architecture that employs a software development kit and an add-in model to collect payment data and communicate with payment processors in a point-of-sale (POS) application to meet new requirements in new markets. Data gathered from an add-in and from the POS application can be combined and then communicated to the payment processor. The payment method can be determined and payment processing routed to different payment processors based on data and schema of data collected is also described. An add-in can also programmatically obtain information from the POS application information about a transaction and authorize a payment. A payment collecting/processing API is the interface between the POS application tender logic and payment collecting/processing logic and defines how a payment collecting/processing add-in interacts with the POS application.