Described are computer-based methods and apparatuses, including computer program products, for dynamic user interface customization. A set of functions for a user interface is stored, each function comprising a function that can be added to the user interface. A first set of data is transmitted to a remote device that causes the user interface to be displayed on the remote device with a predetermined set of functions from the set of functions. Interaction data is received indicative of a user's interactions with the user interface. A second set of data is transmitted to the remote device that causes the user interface to dynamically add a new function from the set of functions to the user interface based on the interaction data, wherein the new function is displayed as a selectable item in the user interface that the user can select to use a function associated with the new function.