Technology is now available for creating affordable sensor networks and infrastructures for ubiquitous computing environments. In the area of ambient assisted living, context-awareness is considered to be a key factor towards creating acceptable solutions that support elderly people in living independently in their homes as long as possible. Unfortunately, at the present state of technology, the design of context-aware products and services requires substantial technical knowledge. Consequently, product designers are often dependent on engineers for implementing prototypes and consequently prototyping their design concepts is a costly and time-consuming process. This paper presents a web-based toolkit that supports product designers in prototyping and configuring interactive context-aware services in multiple homes. The toolkit has been designed and tested in close collaboration with interaction designers. Using the toolkit, designers can make fast design iterations and eventually lower development cost.