The most powerful software decision in an office is not always the subscription, the laptop or the AI assistant. Sometimes it is the file extension at the end of a document nobody thinks about.
.docx. .xlsx. .pptx. .odt. .ods. .odp.
That looks like housekeeping. It is product strategy.
The Document Foundation published a pointed July 17 article arguing that Microsoft Office formats keep users locked into Microsoft’s ecosystem. Microsoft, for its part, says Office supports ODF and that Open XML formats are the default and recommended formats in supported versions of Office. OASIS describes ODF as an open XML-based format intended for office documents, while the European Commission’s newer open digital ecosystem guidance pushes open standards and models in public procurement.
GearPulse’s read: this is relevant because file formats are one of the least glamorous ways software companies keep power. You can migrate apps, switch laptops and cancel subscriptions. But if ten years of contracts, spreadsheets, forms and presentations only behave correctly in one vendor’s software, the real migration project is not software. It is institutional memory.
The file is the workflow
The Document Foundation’s argument is not that Microsoft Office files cannot be opened elsewhere. They usually can. The sharper claim is that “opens” and “reproduces faithfully” are different promises.
Anyone who has moved a serious Word document between suites knows the feeling: the text survives, but a table shifts, a footer breaks, a font changes, a presentation lands one animation away from looking careless. In a family newsletter, that is annoying. In a contract, government form, medical document or court filing, it can become operational risk.
Microsoft’s own support page acknowledges the compatibility tradeoff from its side. Office supports ODF, but Microsoft warns that because Office and OpenOffice-style features are not exactly the same or implemented the same way, saving Office files in ODF can change how users work with the file or sometimes affect content. Microsoft also states that Open XML formats are the default and recommended choice for Office users.
That is reasonable product advice if you live inside Microsoft 365. It is also exactly how defaults become gravity.
| Format choice | Practical benefit | Practical risk |
|---|---|---|
Microsoft Open XML (.docx, .xlsx, .pptx) | Best fidelity for Microsoft Office and Microsoft 365 collaboration | Can make non-Microsoft workflows feel second-class if formatting is critical. |
ODF (.odt, .ods, .odp) | Open standard stewarded through OASIS, suited to vendor-neutral document exchange | May lose some Office-specific behavior when round-tripping from Microsoft apps. |
| Good for final reading and archiving layout | Poor for live collaboration and structured editing. | |
| Plain text / Markdown / CSV | Durable, portable and easy to process | Too limited for many designed documents and spreadsheets. |
The answer is not “everyone should switch tomorrow.” The answer is to stop pretending the default is neutral.
Why this is bigger than LibreOffice versus Microsoft
It is tempting to file the whole debate under old desktop-software rivalry. That misses the point.
A file format controls how work travels. It decides who can read the document without buying the same tool, who can automate it, who can archive it, who can build a competing editor and who gets blamed when the document looks wrong.
This is why governments care. The European Commission’s June 2026 open digital ecosystem guidance says public administrations increasingly depend on their capacity to understand, shape and control the technologies they rely on. It also says the Commission will promote open standards and models in procurement so public authorities can choose solutions rather than be locked into proprietary systems.
That sounds bureaucratic until you imagine a government archive full of documents that only one vendor’s future software can render with confidence. The long-term problem is not whether today’s laptop opens today’s document. It is whether a public record, a school form or a legal file remains usable after procurement cycles, product changes and platform shifts.
The personal annoyance is the signal
The funny thing about format lock-in is that users feel it before they can name it.
You send a slide deck to someone, they say the fonts are broken, and suddenly the answer is “just use PowerPoint.” A school requires a document template, and the safe answer is Word. A contractor returns a spreadsheet with formulas that only behave correctly in Excel, and the open-source alternative quietly leaves the room.
That is not always malicious. Microsoft Office is excellent at many things, and for many teams the most practical choice is still to use the tool everyone else uses. But the repeated tiny friction has a direction. It trains people that compatibility means returning to the dominant suite.
The Document Foundation is obviously not a neutral observer; it is the non-profit behind LibreOffice. But biased sources can still point at real structure. Microsoft has the dominant workflow, the default file formats and the most accurate renderer for the behaviors its own ecosystem produces. That is power even when it is wrapped in standards language.
A better way to think about formats
The practical question is not “which format is morally pure?” It is “what is this document for?”
| Use case | Sensible default |
|---|---|
| Live Microsoft 365 collaboration with Office-dependent features | Use Microsoft formats and accept the ecosystem dependency. |
| Public forms meant to be edited by many tools | Consider ODF or simple web forms where possible. |
| Final published document | Export PDF and keep an editable source in a documented format. |
| Long-term archive | Prefer open, documented formats plus PDF/A where appropriate. |
| Data exchange | Use CSV, JSON or another machine-readable format instead of spreadsheet styling. |
The important move is to make the choice visible. A company can decide Microsoft fidelity is worth the lock-in. A government can decide open formats matter more than perfect Office parity. A school can decide that a required template should not assume one paid suite. Those are policy choices, not invisible defaults.
Why AI makes this matter more
AI assistants are going to make document workflows more automated, not less.
Agents will draft files, extract tables, transform reports, generate slide decks and read archives. The easier a format is to parse and reproduce outside one vendor’s app, the more flexible those workflows become. The more behavior is hidden behind one platform’s exact renderer, the more automation becomes another reason to stay inside that platform.
That is the quiet future of the office suite fight. It is not only humans opening files. It is software reading software’s paperwork.
Bottom line
Your file extension is a power decision.
For many teams, Microsoft Office formats will remain the practical default because the surrounding workflow is already Microsoft-shaped. But The Document Foundation is right about the larger pressure: documents are not inert pieces of paper anymore. They are structured files interpreted by software, and whoever controls the most trusted interpretation has leverage over everyone else’s work.
Use the format that fits the job. Just do it on purpose.