This document discusses the CPaaS.io project, a joint R&D project between Europe and Japan aiming to create an open social city platform. The project aims to develop an open city platform as a service that empowers citizens with their own data and validates the platform with use cases to provide public value. It received 3.2 million euro in funding over 2.5 years from the EU and Japanese government. The platform combines IoT, big data, and cloud services to connect technologies, citizens, and cities.