As digital platforms become ever more central to our lives, the need for public interest digital infrastructure has never been greater. While open source software is a crucial foundation, it alone is not enough to ensure that our digital spaces serve the common good. To realize the vision of a truly digital commons in the European Union – one built on openness, participation, and resilience – we need the active support of public institutions, civil society, and developers for the Fediverse. In this talk, I will explore why federated networks like the Fediverse are essential building blocks for a truly digital commons, especially in the European context. Join me to discover how we can move from open source to open spaces, and help build the digital commons our society needs.