LibreOffice slams rival Euro-Office as a 'de facto ally' of Microsoft blocking, as concerns grow over possible Russian interference

Euro-Office uses Microsoft’s OOXML format by default, which encourages vendor lock-in
LibreOffice calls on the European sovereign to offer a blatantly “free” copy of MS Office
Euro-Office and its parent, OnlyOffice, are mostly created by Russian developers.

The Document Foundation, the organization behind LibreOffice, has publicly criticized Euro-Office over concerns that it does not genuinely promote European digital sovereignty despite its marketing as a viable European alternative to companies like Microsoft Office.

LibreOffice described Euro-Office as a “free clone” of rival Big Tech, stating that its strategy is to imitate Microsoft’s interface and workflows.

By contrast, OpenOffice.org and LibreOffice “are two genuine open source office suites, built from source code that originated in Europe,” founding member Italo Vignoli wrote in an open letter.

Euro-Office scheduled for multiple sovereignty concerns

In the letter, Vignoli criticized Microsoft’s “horrible proprietary OOXML format,” acknowledging its use of the format to impede sovereignty efforts by supporting vendor lock-in. An understandable strategy on the part of a technology provider that, at least historically, has not actively supported sovereignty efforts over clear desires to grow the business.

However, while that is understandable, Vignoli questions why “Euro-Office defaults to the fully proprietary OOXML document format,” arguing that it simply reinforces the Microsoft ecosystem and creates a long-term dependency on the company’s products.

The original announcement described Euro-Office as a “sovereign replacement for Microsoft Office” with an “intuitive interface” and “strong compatibility.” The familiar interface is believed to be intentional to facilitate migration.

European technology companies such as IONOS, Nextcloud, Eurostack, XWiki, OpenProject, Soverin, Abilian and BTactic are behind the initiative.

Security concerns

Another sovereignty concern is the Euro-Office’s potential (if not slightly disconnected) ties to Russia. Euro-Office is actually based on an existing project called OnlyOffice, and was recently separated from that project in March 2026.

cyber news has revealed that up to 99% of the code base can be traced back to developers working in Russian time zones and only a small proportion of the contributions come from the European consortium itself.

Additionally, it appears that the new sovereign project continues to merge select code changes from the initial project, indicating that it is still dependent on Russian software developers.

With this in mind, users might worry about vulnerabilities, malicious code insertion, and broader dependency risks that completely negate the sovereign effort in the first place.

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