In some implementations, a method of providing contactless payments at a point of sale terminal includes: causing a point-of-sale terminal processing a transaction to display a machine-readable code, the machine-readable code encoding a web address; receiving a request from a device that scanned the machine-readable code, the request received at the web address; in response to receiving the request, causing the device that scanned the machine-readable code to output an interface that includes a prompt for input required to complete the transaction; receiving a response to the prompt; and sending an indication of the response to the prompt to the point-of-sale terminal to allow for completion of the transaction based on the response at the point-of-sale terminal through use of a physical token at the point-of-sale terminal.