LibreOffice slams rival Euro-Office as a 'de facto ally' of Microsoft lock-in — as concerns over possible Russian interference rise

• Euro-Office defaults to Microsoft's OOXML format, encouraging vendor lock-in
• LibreOffice calls the European sovereign offering a blatant "freeware" copy of MS Office
• Euro-Office and its origins, 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 the likes of Microsoft Office.

LibreOffice described Euro-Office as a "freeware clone" of its Big Tech rival, claiming its strategy is to mimic Microsoft's interface and workflows.

Conversely, 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.

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Euro-Office slated over multiple sovereignty concerns

In the letter, Vignoli slated Microsoft's "horrible proprietary OOXML format," acknowledging the format's use in preventing sovereignty efforts by supporting vendor lock-in. An understandable strategy by a tech vendor that, historically at least, hasn't actively supported sovereignty efforts over clear desires to grow the business.

However, while that much is understandable, Vignoli questions why "Euro-Office defaults to the fully proprietary OOXML document format," arguing it simply reinforces Microsoft's 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 make migration easier.

European tech firms like IONOS, Nextcloud, Eurostack, XWiki, OpenProject, Soverin, Abilian and BTactic are behind the initiative.

Security concerns

Another sovereignty concern is Euro-Office's potential – if not slightly disconnected – ties to Russia. Euro-Office is actually based on an existing project called OnlyOffice, having only recently parted ways from that project in March 2026.

Cybernews has revealed up to 99% of the codebase can be traced back to developers working in Russian time zones with only a small proportion of contributions come from the European consortium itself.

Additionally, it appears that the new sovereign project continues to merge selected code changes from the upstream project, indicating it's still reliant on Russian software developers.

With this in mind, users could have concerns over vulnerabilities, malicious code insertion and broader dependency risks that totally negate the sovereign effort in the first place.

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