The Ubiquitous Interactor (UBI) addresses the problems of design and development arising around services that need to be accessed from many different devices. In UBI, the same service can present different user interfaces on different devices by separating user-service interaction from presentation. The interaction is kept the same for all devices, and different presentation information is provided for different devices. This way, tailored user interfaces for many different devices can be created without multiplying development and maintenance work. In this paper we describe the system design of UBI, the system implementation, and two services implemented for the system: a calendar service and a stockbroker service.