A key concern in the Internet of Things (IoT) has been the integration of mundane objects in the Internet. Although increasingly interconnected, the IoT ecosystem is largely industry-centered. This leads to the creation of limited and incompatible services disempowering users by hampering their participation. In this thesis, we address this issue by empowering users to create, personalize, and distribute services in the IoT ecosystem. We define a general framework for user empowerment relying on the concepts of People, Places, Things and Applications and study their interactions. These concepts are used as design elements to implement an IoT Service Platform. The general framework, the reference implementation and the evaluation provide the design guidelines for building IoT service platforms enabling user empowerment in the IoT.