The Document Foundation calls the new fork a 'de facto ally of Microsoft' on document lock in. Euro Office's backers say European digital sovereignty is now a stack you build, not a product you buy.
When European governments and companies wanted digital sovereignty, they assumed they would buy it. The launch of Euro-Office 1.0 on June 9, 2026, suggests the model is shifting: sovereignty is becoming something you assemble, component by component, on infrastructure you control.
Euro-Office is not a standalone office suite. It is an editing engine, a fork of OnlyOffice's AGPL-licensed open-source core, that has to be embedded inside a host platform such as Nextcloud Hub, OpenProject, or Proton Docs, per the Euro-Office GitHub project page. The storage, permissions, sharing, and navigation come from the host. For most readers, that means Euro-Office 1.0 reaches them as part of a packaged stack: Nextcloud Hub 26 Spring, IONOS Nextcloud Workspace, or Office.eu, with technical users able to self-integrate the engine on their own Linux servers, as described in ZDNET's coverage of the launch.
The architectural choice is the political one. Euro-Office's backers, including Nextcloud, IONOS, Proton, Open-Xchange, OpenProject, and Tuta, are pitching the project as a cornerstone of European digital sovereignty, an alternative to Microsoft 365 and Google Workspace for public-sector and privacy-conscious deployments (Euro-Office GitHub project page). 98% of IT leaders cite digital sovereignty as a priority, per SUSE/ZDNET figures cited in the launch reporting. The federated-stack framing treats sovereignty as a property of the assembly: who hosts the data, under whose jurisdiction, with which components auditable and open.
The Document Foundation disagrees, on substantive grounds. In an open letter published June 8, 2026, the steward of LibreOffice disputed Euro-Office's "first European open-source office suite" claim (OpenOffice.org dates to 2001 and LibreOffice to 2010) and made a sharper argument: Euro-Office defaults to Microsoft's proprietary OOXML formats (DOCX, XLSX, PPTX) rather than the ISO/IEC ODF standard. TDF called the project a "de facto ally of Microsoft" on document lock-in, because treating OOXML as a first-class format rather than an interchange target entrenches the very dependency European sovereignty is meant to escape.
Euro-Office's own GitHub project page lists DOCX, PPTX, XLSX, PDF, and ODT, ODS, ODP, TXT as supported formats, with OOXML alongside ODF rather than ODF-first. That ordering is the design choice TDF is contesting. Euro-Office backers frame the compatibility-first posture as a practical concession to the documents European offices actually receive. The disagreement is real and worth reading as a debate about open standards, not as a personality dispute.
A second dispute preceded the launch and reportedly resolved in time for it. OnlyOffice vendor Ascensio System SIA initially argued the Euro-Office fork violated AGPLv3 attribution and branding terms; AGPL co-author Bradley Kuhn of the Software Freedom Conservancy sided with the Euro-Office developers, per ZDNET's reporting. The ZDNET piece describes the license question as resolved; no joint statement or Conservancy confirmation surfaced in this research turn, and the resolution claim is worth a fact-check pass before publication.
The "compatibility is not sovereignty" framing comes from TDF's open letter, and it deserves to be taken seriously on its merits. If the goal of a sovereign office stack is to reduce dependency on a single vendor's formats, then shipping an editing engine that treats that vendor's proprietary formats as native is a design choice that cuts against the goal, regardless of where the engine is hosted. Conversely, if the goal is interoperability with the documents European offices actually receive, then ODF-first is a slower path to adoption. Both readings are defensible, and the choice has consequences either way.
An independent reviewer assessed Euro-Office 1.0 as "more of a tech preview than a finished product": the core editor and real-time collaboration work, but integration and configuration are fiddly, OnlyOffice branding is still visible in places, and the menus feel dated, according to the ZDNET review. The reviewer advised against production deployment, which is the right read for anyone considering Euro-Office 1.0 as a one-to-one replacement for Microsoft 365 or Google Workspace today. It is not that, and treating it as such would mislead readers.
What it is, is a building block. For IT leaders and policymakers, the practical questions become: who hosts the data, under which jurisdiction, with which components auditable, and on whose roadmap. A federated stack with an open-source editing engine, a trusted host platform, and ODF as the canonical format is one configuration. A federated stack that defaults to OOXML and trusts host platforms to set the policy is another. The Euro-Office 1.0 launch makes that choice visible in a way that "buy the sovereign suite" never did.
The watch items are concrete. Whether Euro-Office's roadmap moves ODF to a more equal footing, whether Nextcloud and IONOS keep their packaged offerings current, and whether public-sector procurements specify ODF-first as a condition will all shape whether the assembled stack actually delivers on its sovereignty promise. For now, the honest summary is that European office sovereignty in 2026 is a stack, not a product, and Euro-Office 1.0 is one well-publicized piece of it.