Euro-Office and the Quest for Digital Sovereignty: Why Document Formats Matter

Introduction

The launch of Euro-Office in early 2025 was hailed as a significant step toward European digital autonomy. Developed as a collaborative project between Nextcloud and IONOS, Euro-Office forked from ONLYOFFICE to offer a self-hosted, web-based office suite targeting organizations and governments that demand secure, collaborative document editing on their own infrastructure. The project explicitly aims to move away from software with ties to Russia, citing concerns over digital sovereignty. Yet almost immediately, The Document Foundation (TDF), the nonprofit behind LibreOffice, raised a fundamental question: what document format will Euro-Office use as its native format?

The Document Foundation's Concerns

In late March 2025, TDF published an open letter to European citizens, arguing that digital sovereignty is not simply a matter of switching office software vendors. True independence, the letter insisted, requires open document formats, open fonts, and continuity of expertise — none of which automatically come with a vendor change. TDF specifically asked Euro-Office to clarify whether it would adopt the Open Document Format (ODF) as its native format, pointing out that the launch press release made no mention of ODF. The organization received no reply, prompting a pointed thank-you post to ODF contributors while taking a subtle dig at Euro-Office's silence.

The Format Dilemma: ODF vs. OOXML

At the heart of the dispute is the choice between ODF and Microsoft's OOXML. OOXML is designed and controlled entirely by Microsoft, meaning any office suite that defaults to OOXML compatibility remains structurally dependent on decisions made in the United States, regardless of where the software is hosted. ODF, by contrast, is an ISO standard developed openly without a single company controlling it. TDF argues that for European institutions to achieve genuine digital sovereignty, they must commit to ODF as the native format for documents created and shared among public bodies.

What Euro-Office Has (and Hasn't) Said

Euro-Office's GitHub repository does list ODF alongside DOCX, PPTX, and XLSX, so open formats are not excluded. However, the project's FAQ emphasizes “great MS compatibility,” which critics say undermines the goal of breaking free from Microsoft's ecosystem. Supporting a format and making it the native default are two different things — the distinction is crucial for any European institution that truly wants to end its dependency on U.S.-controlled technology rather than simply relocate it to a different server rack.

The Importance of Native Formats for Sovereignty

Choosing a native format goes beyond technical preference. It determines which software can read and edit the files without conversion. If Euro-Office defaults to OOXML, users may unknowingly lock themselves into a format that requires licensing from Microsoft or its affiliates. In contrast, ODF is royalty-free, vendor-neutral, and already mandated by law in several European countries — most notably Germany, which requires all federal agencies to use ODF by 2026. TDF's question is therefore not academic: if Euro-Office aims to serve European public administrations, it must align with these legal requirements.

Euro-Office's Silence and What It Signals

As of now, Euro-Office has not publicly addressed TDF's query about its native format. This silence is itself telling. It suggests either uncertainty about the strategic direction or a reluctance to commit to an open standard that might limit compatibility with Microsoft Office — a major consideration given that many potential users are currently reliant on DOCX workflows. However, by staying silent, Euro-Office risks losing credibility among digital sovereignty advocates and public sector customers who take format policy seriously.

Conclusion: The Real Path to Sovereignty

The debate over Euro-Office underscores a broader truth: digital sovereignty is not achieved by simply hosting software in Europe. It requires deliberate choices about open standards, transparent governance, and long-term independence from proprietary control. The Document Foundation's challenge has put Euro-Office on notice. Whether the project responds by embracing ODF as its native format or continues to prioritize Microsoft compatibility, the question will not disappear — especially as the German ODF mandate takes effect. For European institutions seeking true autonomy, the answer is clear: look beyond where the code runs and focus on what format your documents speak.