The role of affect has become increasingly important in ambient intelligence applications. Developers require means for using multiple tools that support emotion detection and interpretation, which can be used jointly to provide meaningful system responses for the user in varied situations. We introduce Vikara, an extensible software platform that provides developers with uniform interfaces and services so their applications can access the results from existing (or newly implemented) tools for emotion sensing and interpretation. Vikara also provides components that make it possible for platform managers to visually monitor affective states as they are sensed by the various available tools. We have experimented with our platform via the development of applications for emotion detection by using (1) the well-known Facial Action Coding System and a Kinect sensor; and (2) a self-reporting interface for Android-based mobile devices. We report on the initial results of using our platform and discuss ambient intelligence scenarios in which we see potential applications, including user experience and usability evaluation, marketing, distance education and inter-personal communication.