By 2030, the Interoperable Europe Act aims for all key public digital services in EU member states to be interoperable, enabling seamless cross-border information exchange. Open source software is a key tool and lever for achieving the ambitious yet critical goals. Significant investment, guidance, and collaboration will be needed to ensure the European public sector sphere can effectively adopt and sustain open source solutions.

This talk presents findings from an in-depth study of five mature cases where local governments have adopted, developed, and collaborated on open source software from three perspectives:

1. Local governments and public sector organisations as drivers and users of open source solutions.
2. Community actors that enable collaboration and knowledge sharing.
3. Service suppliers (public, private, and civil society) providing technical capabilities for planning, development, maintenance, and operations.

The presentation offers three takeaways for the attendees. First, the case studies show how local government open source projects have evolved through various stages, what challenges they have experienced, how these have been managed, and how sustainability is planned for. Second, a set of archetypes is defined to support actors in identifying their own role and those of others in the open source ecosystem to foster successful open source collaboration in a specific context. Finally, specific recommendations are provided to guide local governments, community actors, and service suppliers to cooperate in developing and supporting open source solutions with the potential to scale cross-border collaboration.

Digital sovereignty—the ability to control and influence one’s digital future and infrastructure—is increasingly at the centre of political and technological agendas. Recent signals, such political signals and shifts in attitude toward non-European cloud providers, underscore a broader momentum. While governments pursue different and sometimes overlapping strategies, open source consistently emerges as a key enabler. Through open strategic autonomy, sovereignty can be gained while fostering interoperability, reuse, and collaboration. Open source provides a path to influence without requiring exclusive ownership, balancing self-reliance with global interconnectedness.

However, leveraging open source effectively requires capabilities and know-how across society and industry. This implies actions at multiple levels: cross-cutting training and workforce development, sustainable business ecosystems, supportive policies and OSPO structures in both public and private sectors, long-term procurement strategies, targeted government facilitation and funding, and investments in the maintenance of foundational technologies. Strategic planning is essential to align these capabilities with societal and industrial goals. This talk will delve into how Europe can grow Digital sovereignty through open source, and leverage the strategic opportunity it provides.