LibreOffice calls rival Euro-Office a ‘de facto ally’ of Microsoft’s lockdown – as concerns over possible Russian interference grow

Euro-Office uses Microsoft’s OOXML format by default, encouraging vendor lock-in.
LibreOffice accuses the European sovereign of offering a blatant “free” copy of MS Office
Euro-Office and its origins, OnlyOffice, are mainly created by Russian developers

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

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

Conversely, OpenOffice.org and LibreOffice “are two true open source office suites, built from source code originating in Europe,” founding member Italo Vignoli wrote in an open letter.

Euro-Office questioned on multiple sovereignty issues

In the letter, Vignoli denounces Microsoft’s “horrible proprietary OOXML format”, acknowledging the use of this format to prevent sovereignty efforts by supporting vendor lock-in. An understandable strategy from a technology provider that, at least historically, has not actively supported sovereignty efforts in the face of a clear desire to grow its business.

However, while this is understandable, Vignoli questions why “Euro-Office defaults to the fully proprietary OOXML document format”, arguing that this simply strengthens 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 meant to be intentional, to make migration easier.

European technology companies like IONOS, Nextcloud, Eurostack, XWiki, OpenProject, Soverin, Abilian and BTactic are behind this initiative.

Security issues

Another sovereignty concern concerns the Euro-Office’s potential – if not slightly disconnected – links with Russia. Euro-Office is actually based on an existing project called OnlyOffice, from which it recently spun off in March 2026.

Cybernews revealed that up to 99% of the code base can be attributed to developers working in Russian time zones, with only a small proportion of contributions coming from the European consortium itself.

Additionally, it appears that the new Sovereign Project continues to merge some code changes from the upstream project, indicating that it is still dependent on Russian software developers.

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

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