Methods, computer program products, and apparatus for open tab transactions. A customer device, e.g., a smart phone, can generate an order for purchasing one or more goods or services from a merchant. A list of the items can be stored in a data structure designated as a tab. The list is routed to a merchant device, e.g., a tablet computer. The customer device can be carried by a user to the merchant. When the user reaches the merchant, the customer device or merchant device can receive a request to add an additional item to the list. The tab remains open and modifiable until the customer device or merchant device receives an input to close it. Payment for the goods or services listed in the modified tab is processed upon closing of the tab.