LibreOffice criticizes Microsoft for using 'complicated' file format to tie down Office users

LibreOffice has been constantly criticizing Microsoft and its tactics lately. This time, the open source office suite continues to accuse Microsoft of "intentionally" using an "unnecessarily complex" file format to retain Microsoft 365 (Office) users.

Few people know that XML is the markup language used by software like Microsoft 365 or LibreOffice to build and define documents. LibreOffice explains:

An XML schema includes the structure, data types, and rules of an XML document, described in an XML Schema Definition (XSD) file. It instructs computers how to read the data and validate it. In theory, XML and XSD together form the foundation for interoperability.

The two office suites go in two different directions. LibreOffice uses the Open Document Format (ODF) - an open standard not controlled by any one company, which produces .odt (text) or .ods (spreadsheet) files.

Meanwhile, Microsoft created its own Office Open XML (OOXML) to support all the proprietary features, creating familiar files like .docx or .xlsx. Interestingly, both formats are actually just compressed ZIP files. You can easily verify this by changing the .docx extension to .zip and unzipping to see the internal structure of the Microsoft 365 file.

LibreOffice argues that XML is supposed to act as 'a bridge,' but Microsoft has made their schema 'so complex that it becomes a barrier rather than a bridge.' They liken it to a public rail system controlled by a monopoly with a system so complex that no one can build compatible trains, making it impossible for competitors to compete. Users don't realize they're being 'held hostage' by these technical barriers.

An example of this complexity is the multi-layered nested structure with confusing naming conventions and a plethora of optional components that make implementing the format a nightmare for third-party developers. Even a simple sentence turns into a maze of nested tags that are nearly impossible to parse correctly, even though the resulting display looks identical.

LibreOffice argues that this 'lock-in' logic is also present in other areas. They link the complex format to Microsoft's forced upgrade to Windows 11, arguing that the Redmond company has no compelling technical reason other than to force users to become dependent. Therefore, LibreOffice urges Windows/Office users to switch to Linux/LibreOffice for more autonomy and freedom.
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Isabella Humphrey

Update 21 July 2025