Methods and apparatus are provided for a scalable user interface system. A user interface is divided into general reusable user interface components and application specific user interface components. Next profiles are created for user interfaces based upon server capabilities and client side device capabilities and reusable user interface components are built for use in multiple profiles. Defined user interface scalability strategies are executed at runtime to build a user interface description using the user interface components. In this way, a user interface can be built from a user interface description by apportioning the building of the user interface description between a server and a client side device using the profiles. At the server, user interface components stored in memory are used to build a first portion of the user interface description while a second portion of the user interface description is built at the client side device and is combined with the first portion received from the server.