This momentum is now backed by political commitment. With the Declaration for European Digital Sovereignty, signed in Berlin, all 27 EU Member States have pledged to reduce strategic dependencies and strengthen Europe’s ability to shape its own digital infrastructure.

And this is not just a political ambition. It reflects a broader public concern: a study published in June 2026 found that a clear majority of Europeans support greater investment in digital infrastructure under European control. In other words, digital sovereignty is no longer an abstract policy goal. It is becoming a shared expectation — from governments, public institutions and citizens alike.

What is driving the shift?

The reasons behind this change are varied. Rising license costs and unpredictable changes to proprietary licensing models certainly play a role, but they are not the only factor — and often not the most important one.

Rather, pressing data protection concerns play a role. As soon as citizens’ sensitive data is processed in U.S. cloud infrastructures, public authorities regularly find themselves in conflict with the strict requirements of the European General Data Protection Regulation (GDPR).

However, open source is not just a shortcut. Free software still needs to be operated professionally, maintained continuously, secured properly and supported reliably. But it creates important conditions for greater independence: source code can be reviewed, data remains easier to migrate, interfaces can be designed more openly and administrations reduce their dependence on individual vendors.

Across Germany and Europe, a growing number of public-sector projects show how open source can be introduced successfully — at different levels, with different priorities and at very different scales.

Schleswig-Holstein: A state-wide strategy at scale

Schleswig-Holstein is the first German federal state to move its entire state administration to open-source software. This is not about replacing one tool with another. It is about building a sovereign digital workplace — one that gives the public sector greater control over its systems, data and long-term IT strategy.

One of the biggest technical tests was the migration of the central email and calendar system. Within six months, more than 40,000 mailboxes containing well over 100 million emails and calendar entries were moved from Microsoft Exchange and Outlook to Open-Xchange and Thunderbird — while operations continued and without any data loss.

The state has also made significant progress in replacing Microsoft Office with LibreOffice. The open-source office suite is now the binding standard for office applications across Schleswig-Holstein’s ministries and public authorities. According to the state government, almost 80 percent of workstations outside the tax administration already use the open-source solution.

Further elements are being added to the strategy. Nextcloud is gradually replacing Microsoft SharePoint as the state’s collaboration platform, while the “+1.Linux Arbeitsplatz” project is preparing and testing Linux as an alternative operating system for workplace devices.

According to the state government, Schleswig-Holstein is already saving more than €15 million in licensing costs. In 2026, this will be offset by one-time investments of €9 million for migration and the further development of open-source solutions. That is precisely what makes the use case so compelling: digital sovereignty requires investment, but it will eventually pay off.

Mecklenburg-Vorpommern: Digital collaboration as a starting point

Mecklenburg-Vorpommern is also taking concrete steps toward greater digital sovereignty. The state has initially focused on collaboration platforms — an area where dissatisfaction with proprietary licensing models is often particularly high. To replace Microsoft SharePoint, it chose Nextcloud. The migration has already been completed for the first 5,000 employees. In the medium term, the platform is expected to be available to more than 50,000 public-sector employees — from state ministries to municipal institutions.

What makes this example especially interesting is the chosen starting point. Mecklenburg-Vorpommern is not beginning with a complete replacement of all workplace systems. Instead, it is focusing on an area that matters to administrative teams every day: collaboration. Sharing files, working on projects together, organizing knowledge and, in the future, adding chat, video conferencing and groupware — these are precisely the areas where many public authorities develop strong dependencies on proprietary platforms.

This architecture is complemented by OpenProject for agile project management and LEA, an administrative chatbot based on OpenWebUI. As a locally hosted AI assistant, LEA is designed to keep sensitive data under the state’s control.

Through its Northern German alliance with Schleswig-Holstein, Mecklenburg-Vorpommern also shows that public administrations do not have to develop or evaluate every solution on their own. They can learn from one another, share experience and create better conditions for open digital infrastructure together.

City of Munich: Optimizing processes at the citizen interface

Munich is one of Germany’s best-known open-source examples. Many still associate the city with LiMux, its pioneering open-source project. That history makes Munich an especially interesting case today: it shows that open source does not always have to begin with a large-scale system replacement. It can also create value exactly where administrative processes become visible to citizens.

One example is Munich’s digital citizen service. Since January 2025, the City of Munich has been using the open-source ticketing system Zammad. When citizens submit an online form, a ticket is automatically created and forwarded to the responsible department. More than 250 of the available online forms have already been integrated into the ticketing system.

With around 70,000 forms filled out online each month, it quickly becomes clear why this step is important: digitization doesn’t end with the online form. What happens next is crucial. With Zammad, a request becomes a traceable process: Citizens can view the processing status, respond to follow-up questions, and submit additional documents. The administration, in turn, gains a better overview of responsibilities, communication, and processing steps.

Munich’s example shows that open source does not have to start with the biggest possible project. It can begin where public administration is most tangible for people: at the point where requests are submitted, processed, answered and made transparent.

Denmark: Pragmatic risk management and dual-track operations

Denmark’s approach to transitioning to open-source software serves as an important case study for migration architecture. The Danish Ministry of Digitalization is testing an open-source alternative to the Microsoft Office suite. The solution being used is Collabora, based on LibreOffice.

At the same time, the Danish Road Traffic Authority, Færdselsstyrelsen, launched the SIA Open pilot project. Around 600 employees are replacing Windows, Office, Teams and Edge with a NixOS-based Linux environment and open-source tools. The state’s broader goal is to migrate up to 15,000 workstations by the end of 2026.

Interesting for public-sector IT leaders: Denmark’s central IT authority, Statens IT, is still keeping the existing Microsoft framework agreement in place. Windows remains available as a fallback layer, and critical legacy applications continue to run on the familiar platform for now.

This dual-track approach is not a compromise in ambition. It is risk management strategy. By running both systems in parallel, Denmark can gradually reduce its reliance on proprietary software while collecting reliable real-world data on compatibility, performance and user experience during live operations.

France: a unified open-source ecosystem for the entire Public Sector

France is taking a particularly strategic approach to digital sovereignty. With LaSuite, the French government provides a collection of digital tools designed for the public sector. It includes applications for collaboration, file sharing, communication, video conferencing, data management and AI-supported work. LaSuite is positioned as an open, secure and public-sector-ready working environment.

One of its most visible components is Tchap, the French government’s secure messaging service. According to LaSuite, Tchap is already used by around 600,000 public-sector employees, while its product page now refers to more than 800,000 users.

France is also building its own infrastructure for video conferencing. The state-provided solution Visio is planned to be rolled out across all government services by 2027.

France’s example shows that open source is not just about replacing individual applications. It is about creating a coherent digital toolbox for the public sector — one that is secure, interoperable and aligned with the public mission.

Barcelona: Open source as a principle for digital citizen participation

The Catalan capital is widely seen as a European pioneer in ethical, values-driven digital policy. Barcelona was the first city in the world to officially endorse the United Nations Open Source Principles, sending a clear signal in favor of digital sovereignty, public control over data and technology policies that are more closely aligned with the common good.

This step builds on a strong foundation of mature open-source systems. These include Decidim, an open-source platform for digital citizen participation, and Sentilo, a platform for sharing sensor data in smart-city environments. The city’s websites are also now based on the open-source CMS Drupal.

Decidim in particular shows that free software in public administration can be far more than a technical replacement for proprietary solutions. The platform was created out of a need to make digital citizen participation more transparent, more traceable and better connected with offline participation formats.

Barcelona has become a beacon for cities that see open technologies as the foundation for more democratic, transparent and reusable digital government. Here, open source is used not only as a software model but as a principle for public digital infrastructure: controllable, adaptable, and, in the best case, jointly developable.

Summary: pragmatism trumps ideology

These best practices show that there is no single blueprint for digital sovereignty. Schleswig-Holstein is taking a broad strategic approach, Mecklenburg-Vorpommern is starting with collaboration, Munich with digital citizen services, Denmark with pragmatic pilot projects, France with government-wide tools, and Barcelona with open digital participation. The right starting point is not the same for everyone. What matters is identifying dependencies and taking action where open solutions can create real value.

At the same time, one thing becomes clear: public administrations do not have to reinvent the wheel. The greatest strength of open source lies in collaboration. Cities, regions and national governments can adopt proven architectures, establish shared standards and pool development resources. This turns the transition from a supposed all-or-nothing decision into a manageable, step-by-step process.