LibreOffice developer criticizes Microsoft for proprietary Office formats again

The Document Foundation says Microsoft's OOXML format creates long term vendor lock-in and threatens digital sovereignty for users and governments.

In the past, LibreOffice developer and custodian, The Document Foundation (TDF) has routinely criticized Microsoft for enforcing its proprietary Office standards on customers and has also taken aim at developers which indirectly support Redmond's practices. Recently, it argued that Euro-Office should default to Open Document Format (ODF), and that Microsoft's proprietary OOXML format is awful due to various reasons. It also forced the European Union (EU) to add an open document option for procuring feedback rather than only providing an Excel template. Now, TDF has taken a dig at Microsoft again, highlighting the potential negative impacts of the company's lock-in strategy.

At the heart of TDF's latest blog post is once again a reminder that customers are essentially being locked into a proprietary, non-standard format due to the prevalence of Microsoft Office formats like XLSX, DOCX, and PPTX. The developer claims that when you save a file to your PC in either of these OOXML formats, you are choosing that non-standard format that results in a loss of your digital sovereignty.

This is because Microsoft controls that particular format, the fonts included in that document, and more. Since OOXML is not an open standard according to standard definitions, Microsoft can make undocumented changes to it or extend functionality in a way that benefits Microsoft Office apps but inconveniences other competitors. This is also why a Microsoft Office document may appear perfectly in Redmond's own software, but loses formatting, fonts, and alignment when opened in other platforms like LibreOffice. This forced friction technically ensures that people have a poor experience with Microsoft Office competitors and end up returning to Redmond's software just so they can reliably open their documents correctly.

TDF has then dived into the history of how Microsoft managed to get OOXML standardized. We have covered it multiple times previously, so if you're still interested, you can check out the developer's blog here.

The LibreOffice developer has also made the case against enterprise use of OOXML. Basically, if a general user sees a misaligned document in an ODF-default software like LibreOffice, they will mostly be annoyed. However, this inconvenience can have a major impact on documents that are being used in government and public offices, as well as law firms. As such, when these enterprise users begin to save documents in Microsoft's format, they are essentially handing over the keys to their digital sovereignty to Redmond. These documents are readable right now because Microsoft continues to support the format, but what happens if things change a couple of decades down the line and Redmond loses interest in maintaining its own format?

All in all, TDF has once again emphasized that users should leverage open software, formats, documents, and fonts so that they are not locked in to a particular vendor like Microsoft. ODF is LibreOffice's answer to OOXML, which is not technically complex to develop and maintain, but to choose it and associated document formats "requires a conscious decision by someone with the authority to do so."

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Posted Sunday 19 July 2026 at 7:35 am AEST (my time).

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