This talk will introduce “CityConnect” — an open-source urban service app developed with Flutter and promoted by the Department of Information Technology, Taipei City Government. Using this case study, I will share the challenges, implementation process, and policy implications of adopting open source in the public sector, as well as the various possibilities for citizen participation. This is not a coding tutorial, but a story about the spirit of open source, public governance, cross-sector collaboration, and how we can empower citizens to help improve digital city services. The talk will also briefly review similar initiatives in other cities around the world and explore the future prospects of open source policy in Taiwan.