OrganiCity offers a new paradigm to European digital city making. Built on and extending the FIRE legacy, this project seeks to build a strong foundation for future sustainable cities through co-creation by a wide range of stakeholders. Globally, Europe is a champion of sustainable, inclusive and open societies. The digital age enables us to push this position further and to rethink the way we create cities and facilitate living by integrating many complex systems. OrganiCity combines top-down planning and operations with flexible bottom-up initiatives where citizen involvement is key. So far, this has been difficult to achieve. Previous attempts to scale informal one-off projects or broaden single community projects have failed. By focusing on the city as a sociotechnical whole, OrganiCity brings software, hardware and associated human processes flexibly together into a new living city that is replicable, scalable, as well as socially, environmentally and economically sustainable. Three clusters – Aarhus (DK), London (UK) and Santander (ES) – recognised for their digital urban initiatives, bring their various stakeholders together into a coherent effort to develop an integrated Experimentation-as-a-Service facility respecting ethical and privacy sensitivities and potentially improving the lives of millions of people. The OrganiCity consortium will create a novel set of tools for civic co-creation, well beyond the state of the art in trans-disciplinary participatory urban interaction design. The tools will be validated in each cluster and integrated across the three cities. In addition to citizen-centric join of testbeds, partner technologies and enhancements, two open calls with a budget of €1.8M will permit 25-35 experiments to use the new facility and co-creation tools. The aim is to grow sustainable digital solutions for future cities that are adjusted to the culture and capacities of each city unlocking amended services and novel markets.