Today's mobile and embedded devices are Internet-connected, and have decent computing power, which creates a possibility for complex, cooperative multi-device platforms. Yet, from user's perspective, it seems that we are not freed to use different technologies seamlessly and without thinking. From developer's perspective, on the other hand, building seamlessly communicating devices requires implementing coordination process separately in an application specific fashion, and yet the devices can only communicate through these specific apps that are not aware of each other.In this paper we introduce Orchestrator.js middleware, which is a tool for readily building multi-user, and multi-device applications in heterogeneous environment. This new lightweight and agile middleware is designed to support Social Devices concept, which aims to bring people together, and increase social interactions when people are co-located. With a concrete example, we also describe the process of building and implementing Social Devices applications with embedded and mobile devices.