Office, Groupware & Communication

Sovereign Workplace vs. Microsoft 365

18.02.2026

Microsoft 365 has over 400 million paid seats worldwide. In European public administration, its market share is even more dominant — estimates run north of 80 %. Email, calendar, documents, video conferencing, messaging: the entire daily workflow of most European civil servants runs on a US platform, under US jurisdiction, governed by licence terms that include compliance with US export control laws.

This is, by any measure, a vendor lock-in situation of historic proportions. And for a long time, it was simply accepted — because the alternatives were not ready, or not good enough, or not integrated enough to compete.

That is changing. Not overnight, and not without problems. But across Europe, three governments — Germany, France, and the Netherlands — are building open-source workplace platforms that are beginning to look like genuine alternatives. Other countries — Austria, Denmark, Schleswig-Holstein — are deploying individual components with measurable success.

The question is no longer whether sovereign alternatives exist. It’s whether they’re good enough — and whether the total cost of migration, including operational overhead, justifies the switch.

What Do You Actually Need?

Before evaluating any alternative, the right question is not “which Microsoft 365 replacement is best?” but: what do you actually need? The answer determines which tools make sense — because the open-source landscape is not a single product but a set of specialised components.

If your primary need is groupware — calendar, contacts, email, task and project management — EGroupware has been a dedicated groupware solution since 2003 (building on phpgroupware roots from 2000). It is mature, actively developed, and designed for exactly this use case. Organisations whose pain point is calendar/contacts/project management rather than file sharing should evaluate it before anything else.
If your primary need is file synchronisation and sharing with growing groupware capabilities — Nextcloud is the standard. Originally forked from ownCloud in 2016 to focus on file management, Nextcloud has since expanded significantly into calendar, contacts, mail, and collaborative editing. It is the most widely deployed open-source collaboration platform in European public administration.
If your primary need is messaging — alternatives to Slack and Teams — the landscape includes Matrix/Element (decentralised, end-to-end encrypted, used by the French government and the German Bundeswehr), Mattermost (self-hosted Slack alternative with an open-source core), Rocket.Chat (self-hosted, open source), and Zulip (open source with topic-based threading, useful for teams that need structured conversations). Matrix has the strongest sovereignty story; Mattermost has the most polished Slack-like experience.
If you’re a German public sector organisation looking for an integrated “sovereign workplace” — openDesk is the government-backed answer, discussed in detail below.

This is not an academic taxonomy. It’s a practical triage. Most organisations waste time evaluating the wrong tools because they conflate “groupware” with “file sharing” with “office suite.” Getting the category right before choosing a product saves months of misguided pilots.

The Big Three: openDesk, LaSuite, MijnBureau

openDesk: The German Approach

openDesk is the German government’s answer to Microsoft 365. Developed by the Centre for Digital Sovereignty (ZenDiS), a subsidiary of the Federal Ministry of the Interior, openDesk integrates multiple independently developed open-source projects into a unified workplace:

Nextcloud for file synchronisation and sharing
Open-Xchange for email and calendar
Collabora Online for browser-based document editing
Jitsi for video conferencing
Element/Matrix for messaging

Version 1.0 was released in October 2024. The ambition is clear: a complete, sovereign replacement for Microsoft 365.

Let’s be direct: integration is the hard part. Each of these components is a mature product on its own. But stitching them together into a user experience that feels like a coherent suite — rather than six products with six different design languages — is technically demanding. The seams show. Users accustomed to the tight integration of Microsoft 365 (open a Teams message, click a file, it opens in Word Online, with co-authoring, comments, version history — seamlessly) will find openDesk’s integration less polished.

This is not a failure — it’s a consequence of the architectural decision to integrate existing best-of-breed components rather than building a monolithic suite from scratch. The trade-off is sovereignty and flexibility versus polish and integration depth.

LaSuite: The French Way

LaSuite, developed by DINUM (the Interministerial Directorate for Digital Affairs), takes a different approach. Instead of integrating upstream projects as-is, France built custom forks with a consistent user interface. The result looks and feels like a single product — because, at the presentation layer, it is.

This approach solves the coherence problem that openDesk faces. But it creates a different one: maintaining custom forks requires ongoing development effort, and every upstream update must be evaluated and potentially re-integrated. France has the institutional capacity (DINUM employs a substantial engineering team) and the long-term funding commitment to sustain this. Whether smaller countries could replicate the approach is doubtful.

The suite continues to grow: in February 2026, the open-source spreadsheet and database tool Grist joined LaSuite, reaching 20,000 monthly active users across 15 ministries — a tenfold increase in one year.

MijnBureau: The Dutch Synthesis

MijnBureau is the Netherlands’ sovereign workplace, combining components from both openDesk and LaSuite. It is the newest of the three and benefits from learning from both predecessors.

The Crucial Feature: Federation

The most important technical achievement of these three platforms is not any individual component — it’s the ability to federate. A German civil servant on openDesk can collaborate on a document with a French colleague on LaSuite, or a Dutch colleague on MijnBureau, without the data leaving European sovereign infrastructure.

This is what reduced vendor concentration looks like in practice: not isolation, but interoperability across independently operated platforms — with no single provider controlling the entire collaboration chain.

Tchap: The Quiet Revolution in Government Messaging

While the workplace platforms generate headlines, one of the most significant sovereign deployments in Europe has happened with remarkably little fanfare.

Tchap is the French government’s instant messenger, built on the Matrix protocol and developed by DINUM. It has been available since 2019, but the decisive step came in September 2025, when French Prime Minister’s circular n°6497/SG made Tchap mandatory for interministerial communication.

The numbers: over 600,000 French government employees now use Tchap. The end-to-end encrypted, decentralised messenger has replaced — or at least supplemented — WhatsApp, Signal, and Teams for official government communications.

The German Bundeswehr followed a similar path with BwMessenger, also Matrix-based, serving the armed forces. The German healthcare system (gematik) adopted Matrix for the TI-Messenger. These deployments demonstrate that Matrix — often dismissed as “too technical” for mainstream adoption — can scale to hundreds of thousands of users in environments with strict security requirements.

The lesson from Tchap is instructive: it succeeded not because it was technically superior to Teams or WhatsApp (in user experience, it arguably isn’t), but because the concentration risk of relying on US-hosted platforms for government communications was judged unacceptable — and the decision was backed by a binding mandate. The French government didn’t ask civil servants whether they preferred Tchap. It told them to use it.

Austria: A Quiet Migration

In 2024, the Austrian Federal Ministry of Climate Action (BMWET — now restructured) completed a migration of 1,200 employees to Nextcloud — in four months. The approach was pragmatic: Nextcloud for internal file sharing and collaboration, with Microsoft Teams retained for external meetings where partners expected it.

This hybrid model is notable because it acknowledges reality: most organisations cannot cut ties with Microsoft overnight. External partners, contractors, and citizens expect to join Teams meetings and receive .docx files. The Austrian approach shows that sovereignty can be pursued incrementally: move internal workflows to open-source tools while maintaining interoperability with the Microsoft-centric world outside.

Denmark: The Full Commitment

Denmark has gone further than any other Western European country in explicitly reducing Microsoft dependency at the national level. In the summer of 2025, Digital Affairs Minister Caroline Stage Olsen announced a government-wide rollout of LibreOffice, with the cities of Copenhagen and Aarhus following suit at the municipal level.

The minister’s statement was unusually blunt for a government official: “We must never make ourselves so dependent on so few.”

Denmark’s approach extends beyond the office suite. The government is evaluating alternatives across the stack — cloud, messaging, identity — with a stated goal of ensuring that no single non-European vendor is indispensable. The results will take years to fully materialise, but the institutional commitment is clear and public.

Microsoft’s Response: 365 Local

Microsoft is not standing still. In June 2025, the company announced Microsoft 365 Local — an on-premises deployment option designed to address sovereignty concerns. Additionally, Microsoft’s “National Partner Clouds” — Bleu in France (Orange/Capgemini) and Delos Cloud in Germany (SAP/Arvato) — offer Microsoft 365 operated by European entities under local jurisdiction.

These are significant moves. They demonstrate that Microsoft takes the sovereignty argument seriously enough to restructure its deployment model for the European public sector market. The strategic logic is straightforward: better to offer Microsoft 365 under European control than to lose customers to openDesk or LaSuite entirely.

For European governments, this creates a genuine choice: adopt an open-source sovereign workplace (higher integration effort, lower dependency) or adopt a sovereign-operated Microsoft 365 (lower migration effort, continued software dependency). The answer depends on how far one wants to push the sovereignty argument. If the concern is jurisdiction — where data is stored, who can access it — Bleu and Delos address it. If the concern is dependency — reliance on a single vendor’s software, update cycle, and product roadmap — they do not.

Document Editing: The Persistent Gap

Document editing is where the rubber meets the road. Users don’t evaluate sovereignty arguments — they evaluate whether their spreadsheet opens correctly.

Three open-source document editors compete in this space:

LibreOffice is the desktop standard — mature, capable, and deployed on 30,000+ PCs in Schleswig-Holstein and 150,000 Italian military workstations. Its native format is ODF (an ISO standard). Microsoft format compatibility is good but not perfect — complex .docx and .xlsx files occasionally lose formatting.

Collabora Online brings LibreOffice to the browser, enabling real-time collaborative editing. It integrates with Nextcloud and is a core component of openDesk. The experience is serviceable but not yet at Google Docs level for real-time co-authoring.

OnlyOffice was designed from the start for browser-based editing and offers better Microsoft format compatibility than Collabora. The trade-off: less mature ODF support and a different licensing model (AGPL core, proprietary enterprise features).

For organisations choosing between them: Collabora Online if you’re committed to the LibreOffice/ODF ecosystem; OnlyOffice if Microsoft format compatibility is the priority. Both can be self-hosted. Neither fully matches Google Docs for real-time collaboration fluidity — though the gap is narrowing with each release.

Email: The Sovereignty Elephant

Email deserves special attention because it’s simultaneously the most important communication channel and the hardest to migrate.

Running a self-hosted email server is technically straightforward. Making it reliable is another matter. Deliverability — whether your emails actually reach recipients’ inboxes — depends on IP reputation, SPF/DKIM/DMARC configuration, and the willingness of Google and Microsoft to accept your mail. New mail servers with low-reputation IP addresses routinely see legitimate emails classified as spam.

This creates a perverse dynamic: the more organisations self-host email, the better deliverability becomes for everyone. But each individual organisation faces a cold start problem. The practical solution for most organisations is not self-hosting but choosing a European email provider — Mailbox.org, Posteo, Proton Mail, Open-Xchange — that handles deliverability professionally while keeping data under European jurisdiction.

Schleswig-Holstein’s migration to Open-Xchange for email, completed in October 2025, demonstrates that large-scale government email migration is feasible. But it took years of planning and a dedicated team.

The TCO Question

Advocates of open-source workplace solutions sometimes claim they’re “free.” They’re not. The total cost of ownership includes migration, training, ongoing maintenance, support contracts, and — most significantly — the expertise to operate a multi-component infrastructure.

Microsoft 365 bundles everything: the software, the hosting, the updates, the support, the security, the compliance certifications. The price is visible and predictable. An open-source stack unbundles these — which means lower licence costs but higher operational costs. For organisations with strong internal IT teams, the equation often favours open source. For organisations that rely on outsourced IT, it may not.

Schleswig-Holstein’s numbers provide a reference point: approximately €9 million in one-time investment, offset by estimated annual savings of €15 million — primarily from eliminated Microsoft licence costs. But Schleswig-Holstein has invested heavily in internal expertise. Organisations without that capacity would face higher costs for external support.

The bottom line: open-source is not cheaper for everyone. It’s cheaper for organisations willing to invest in competence. For the rest, it shifts costs from licences to people — which may or may not be an improvement.

What Works, What Doesn’t

Based on the deployments across Europe, a pattern emerges:

What works:

Messaging (Tchap/Matrix): Proven at scale in government, with E2EE and federation. The 600,000+ users in the French government demonstrate viability.
File sync (Nextcloud): Mature, well-documented, widely deployed. The Austrian BMWET migration shows it can be rolled out quickly.
Office suite (LibreOffice): 20+ years of development, deployed at massive scale. The document compatibility gap is manageable with planning.
Email (Open-Xchange): Schleswig-Holstein’s complete migration proves feasibility for large deployments.

What’s improving but not there yet:

Browser-based collaborative editing (Collabora, OnlyOffice): Functional but not yet matching Google Docs or Microsoft Office Online for real-time co-authoring fluidity.
Integrated workplace (openDesk, LaSuite): Released and working, but integration polish is still catching up to Microsoft 365’s seamlessness.

What remains hard:

Fully replacing Microsoft Excel: Complex spreadsheets with macros, VBA, and Power Query remain a pain point. LibreOffice Calc handles most cases but not all.
Video conferencing at scale: Jitsi works well for small meetings but doesn’t match Teams or Zoom for large events with hundreds of participants.
Migration itself: The technical migration is the easy part. User training, process adaptation, and overcoming institutional resistance are the real challenges.

What Follows

The sovereign workplace is no longer vapourware. openDesk 1.0 is deployed. LaSuite is in production across French ministries. Tchap has 600,000+ users. Schleswig-Holstein has migrated 30,000 workstations. Denmark has begun its migration.

The core components work. The remaining gaps — integration polish, advanced spreadsheet compatibility, large-scale video conferencing — are narrowing. The harder obstacles are organisational: user training, institutional resistance, and ensuring the decision survives changes in leadership, as Munich demonstrated.

For organisations considering the move, the maturity assessment above translates directly into a prioritised action plan:

Start now (mature, proven at scale):

Deploy Element/Tchap for internal messaging. 600,000 French civil servants use it daily. The risk is low, the sovereignty gain is immediate, and it reduces dependency on Teams for one of the highest-volume communication channels.
Switch to ODF and LibreOffice for document creation. Schleswig-Holstein has migrated 80 % of 30,000 workstations. Do this before touching anything else — it decouples your documents from Microsoft formats.

Start a pilot this year (functional, improving rapidly):

Deploy Nextcloud for file sync and sharing. Mature and self-hostable. Evaluate whether it meets your collaboration needs or whether you need openDesk’s broader integration.
Test Collabora or OnlyOffice for browser-based document editing. Functional for most use cases, though real-time co-authoring is not yet at Google Docs level.

Plan in years, not months (released but still maturing):

Full openDesk/LaSuite deployment as a Microsoft 365 replacement. The integration works but the seams show. Plan for a 2–4 year migration with gradual adoption.
Replacing complex Excel workflows (macros, VBA, Power Query). Evaluate case by case — some will migrate cleanly, others will require process redesign.

The cost of waiting: Every year you delay costs the equivalent of your Microsoft licence fees — fees that Schleswig-Holstein is saving €15 million annually by having already moved. If Microsoft raises government pricing by 30 % at your next Enterprise Agreement renewal — as they did for commercial customers in 2023 — those numbers get worse. The question is not whether to start, but which component to start with.

Sources

Topic overview: Office, Groupware & Communication