Whenever a user, a government, a school or a business chooses the format in which to store and exchange its digital documents, it is not merely making a technical decision, but is placing a bet on the kind of digital infrastructure on which it will depend in the future.

In this sense, ODF and OOXML are not two equivalent options on the same shelf, but two radically different solutions: one geared towards a future of openness, interoperability and digital sovereignty, and the other towards a past of defending a vendor’s dominant market position through user lock-in.

ODF: designed to be open and transparent

Open Document Format was conceived from the outset to be an open standard. It was designed and developed by the community under the auspices of OASIS, and subsequently ratified by ISO, to be implemented by anyone, on any platform, without royalties, without hidden dependencies and without the permission of any single company.

These are not trivial technical details, but a statement of political and economic strategy embedded within the format itself.

ODF is based on a clean XML schema, easy to read even by non-technical users and reusable. Colour naming follows standard web conventions, and its architecture reuses components from widely adopted open standards. The format was designed to work within an open and transparent infrastructure, not against it.

When a public administration archives a document in ODF format, it can be certain that any future government, any future open-source or proprietary application, and any future platform will be able to read, manage, process and transform that document, because the format specifications are publicly available, and are clear, complete and free from restrictions.

In this sense, the commitment to ODF is a forward-looking one, because it is in line with the evolution of technologies and infrastructure based on open-source software, and with the European agenda on digital sovereignty.

OOXML: designed to preserve the past

OOXML, or Office Open XML, was not designed for interoperability, but to do something very specific: to encode Microsoft Office’s binary formats in XML in such a way as to allow Microsoft to claim compliance with the standard without relinquishing control over users through lock-in.

This origin story is not ancient history, but dates back to the period between 2006 – purely by coincidence, the year the ODF format was approved by ISO – and 2008, the year of the farcical event known as the Ballot Resolution Meeting which led to the approval of OOXML by ISO, and is written into all versions of the specification.

OOXML Transitional, the variant that virtually all Microsoft Office documents use in practice, and the only one available today, is explicitly defined as a compatibility layer with legacy binary formats (the now-forgotten DOC, XLS and PPT, which were nothing more than the saving of working memory to disk), and contains thousands of undocumented elements, format-specific exceptions, and references to legacy Microsoft systems that no third party can fully replicate.

The specification itself acknowledges that Transitional documents may contain elements whose behaviour is ‘legacy’ and whose correct display requires knowledge of Microsoft’s proprietary systems. In short: to implement OOXML Transitional correctly, one must decode thirty years of Microsoft Office history, something that no one except Microsoft can do, and no one ever will.

In this sense, the choice of OOXML is not a gamble but a backward-looking choice, because the format is only open in appearance – but it takes very little, just a bit of goodwill, to realise that it is completely closed – and was designed to be a lock-in mechanism.

Two completely different standardisation paths

OOXML’s path to ISO ratification is a catalogue of everything that should never happen during a standardisation process, starting with the Fast Track method. One comment was: “It will be truly sad if ISO lowers its standards so far that it will accept this monstrosity”.

Another comment, from a member of the ISO Technical Committee that approved OOXML, sums up the format’s problems: “The trouble with OOXML is not just that the document itself is monstrously huge. The current OOXML format has a number of technical problems which have been listed in detail elsewhere. Another problem is that the specification itself is not written as a standard, but more as the sort of technical documentation you’d expect to find for a commercial product. This will cause serious interoperability problems in practice, and since interoperability is the whole point of a standard, that’s not acceptable”.

The market has confirmed what the standardisation process had sought to conceal: OOXML Transitional never delivered the interoperability it promised, and this is confirmed by content loss, rendering differences and various other incompatibilities between Microsoft Office’s implementation and those of third parties, which are persistent and still documented today. A true standard should be perfectly reproducible by following its specification, and should not require reverse engineering or trial-and-error approaches.

ODF, by contrast, has followed the standard ISO standardisation process, and for this reason it is the format recommended by the EU Interoperability Framework, by the German Deutschland-Stack – which mandates it alongside PDF/UA at all levels of public administration – and by a growing number of national frameworks, which have independently concluded that true interoperability requires a genuinely open standard, one that meets the definition of a standard such as ODF.

ODF is “forward-looking”

A forward-looking format is one that reduces future dependency, not one that reinforces it. It is a format that can be used without requiring knowledge of a single vendor’s proprietary technologies. It is a format that a public administration can confidently hand over to its citizens, its archives and its successors.

ODF meets these criteria. Its architecture is transparent, its schemas are clean and its governance is genuinely open. Its various implementations demonstrate every day that it can be implemented fully and faithfully by projects that are very different from one another, not because they have reverse-engineered it but because the specifications are complete and easily understandable.

A “backward-looking” format, by contrast, is one that ties the future to the commercial strategies of a single vendor. In this sense, OOXML Transitional is an archaeological artefact that preserves the past at the expense of the future. Organisations that adopt it as a standard are betting – or perhaps merely hoping – that Microsoft’s roadmap, Microsoft’s pricing and Microsoft’s platform choices will remain unchanged indefinitely.

It is a risk that no government, business or institution – or indeed any individual concerned about the long-term integrity of their data – should feel comfortable taking.

The problem with “alternatives” that aren’t really alternatives

The OOXML-based lock-in has a second, more subtle dimension – and one that is far more dangerous for users – which deserves to be explained: the role of software that presents itself as an alternative to Microsoft Office, but which uses OOXML as its default native format.

This is a biased technical choice. When an office suite, whether proprietary or “nominally” open source, sets OOXML as the default format for documents, it does not offer a way out of the Microsoft ecosystem, but actually reinforces it. Every OOXML file created by a non-Microsoft application is a file that validates OOXML as a standard, which feeds into Microsoft’s narrative on interoperability and makes migration away from the Microsoft format stack marginally more difficult.

The real alternatives—applications that take interoperability and open standards seriously—use ODF as the default and treat OOXML as a compatibility layer for import/export, not as a native format. The distinction is important: it is the difference between supporting the ecosystem of open formats and entrusting one’s format strategy to Microsoft’s legacy architecture, whilst calling it openness.

Germany has chosen

The German mandate on the Deutschland-Stack is the clearest signal in recent times of the direction European policy is taking. By mandating ODF at all federal, state and municipal levels, Germany has institutionalised what advocates have been saying for at least twenty years: that open standards are a prerequisite for digital sovereignty, not an optional preference.

The mandate is not against Microsoft, but in favour of sovereignty, because it asserts that government documents belong to the state, and not to a single vendor. Citizens’ data must remain readable forever, and cannot in any way be subject to a software licence. Therefore, the document format must allow public administrations to make an independent choice, and to migrate without the format itself posing an obstacle.

The path forward is clear

ODF is the format of digital sovereignty, and of an open, transparent and interoperable public infrastructure. It was designed for a future in which no single vendor can control the documentary level of civilisation.

OOXML is a format closely tied to Microsoft’s corporate history, translated into XML and ratified amid controversy. It was designed to ensure that the future remains compatible with Microsoft’s past, dramatically reducing freedom of choice for governments, organisations, businesses and individuals, and limiting ownership of their documents.

Germany has made ODF mandatory as the standard format for documents within its sovereign digital infrastructure. The decision is incorporated into the Deutschland-Stack, the framework governing the development, procurement and management of digital systems for public administration at all levels. This is neither a pilot project nor a recommendation from a working group, but a mandate backed by the federal government and the coalition agreement.

The official document has been published by the IT-Planungsrat, the central political steering body comprising the federal government and state governments, which promotes and develops common, user-oriented IT solutions for efficient and secure digital administration in Germany: https://www.it-planungsrat.de/beschluss/b-2026-03-it.

At this point, the question for all other European governments is clear: what are you waiting for? With this decision, the distinction between those who care about digital sovereignty and those who do not becomes stark.

There are no more excuses

Over the years, public administrations in Europe have accumulated a series of tired excuses, long since overtaken by the facts, for not making standard and open document formats mandatory. Let’s examine them one by one.

ODF isn’t mature enough. ODF has been an ISO standard since 2006. It is now at version 1.4, with active development, a broad ecosystem of implementations and adoption by numerous national governments, the European Parliament and major public administrations worldwide. The maturity argument has long been superseded.

Changing the document format requires staff retraining. The explicit principle of Germany’s sovereign stack is to reduce the effects of lock-in. If the objection is the cost of retraining, you are saying that the commercial interests of the dominant supplier outweigh those of citizens and institutions. This is an acceptable position in the private sector, but inadmissible in the realm of public policy.

The market standard format guarantees interoperability. The market standard, adopted uncritically by public administrations without any verification of its characteristics, is a proprietary format designed for lock-in rather than interoperability, to the extent that it was approved by ISO under the name OOXML Transitional because it contains proprietary elements. ODF, by contrast, is interoperable by definition, and as such has evolved over the years.

We are bound by existing procurement contracts. Contracts come to an end, whilst regulatory frameworks are renewed, and today, faced with the need to ensure European digital sovereignty, the time has come to integrate open standards into them, without waiting another decade for the next renewal cycle, whilst continuing to pay for access to documents that administrations have created using public money.

Today, none of these objections hold water anymore. Germany’s decision demonstrates that even a large and complex federal government can take an important step in the right direction. The obstacles are political, not technical.

The European policy framework

The transition from proprietary formats to standard, open formats for documents, incidentally, is not a radical choice, but an alignment with decisions already taken by European institutions, contained within various laws or regulations that have already been approved.

The European Interoperability Framework (EIF) – the reference document for interoperability in public services – requires the use of open standards and calls for the avoidance of formats that create dependency on a single supplier. The EIF does not explicitly mention Open Document Format, but the logic of the document leads to the choice of ODF.

The Cyber Resilience Act (CRA), the Network Information Security 2 (NIS2) and the Digital Operational Resilience Act (DORA) state that European digital infrastructure must be built using controllable technologies. Documents are the means by which decisions are recorded and communicated, and form part of the infrastructure; they should therefore be in a standard, open format that is easy to control. This is another example of legislation that does not explicitly mention the Open Document Format, but whose logic leads to the choice of ODF.

Finally, the Interoperable Europe Act (IEA), which came into force in 2024, defines the legal framework for interoperability between EU public administrations and explicitly cites open standards, which – in the context of documents – means ODF and not OOXML, which, even if considered a standard (by a stretch of the imagination), is certainly not open.

Germany has linked these three points. The Deutschland-Stack identifies ODF not as an ideological choice but as a key element of a sovereign, interoperable digital infrastructure aligned with Europe. Other EU governments operating within the same regulatory and political context should apply the same logic.

The current situation in EU countries

Germany is not the only country to have taken steps towards open document standards, although the Deutschland-Stack is the most comprehensive and structurally integrated commitment seen at national level.

France made ODF mandatory in the 2009 Référentiel Général d’Interopérabilité, with subsequent updates strengthening this requirement. The French public administration has a legal obligation to use open formats in its dealings with citizens and between agencies.

The Netherlands, Sweden, Norway and Denmark have all, at different times, adopted policies recommending or requiring open document formats in public administration. In 2014, the United Kingdom made ODF mandatory for government documents, and the decision has never been revoked.

Even the Guidelines for the Digital Administration Code, issued in 2023 by the Italian Government’s Agency for Digital Italy (AGID), would define open standards for documents in such a way that only Open Document Format is included in the list, but these are almost always disregarded without reason by public administrations.

Thus, EU governments that seriously examine the issue tend to reach the same conclusion: ODF is the appropriate standard document format for a sovereign and interoperable public administration. What varies are the levels of implementation, and the willingness to see it through when proprietary vendors put up resistance through intense lobbying.

The Deutschland-Stack raises the bar, integrating the choice of ODF into a comprehensive, cross-cutting sovereign infrastructure framework, based on explicit architectural principles and supported by coordinated decisions at every level of the federal system. This is the model to follow.

Our call to action, which should be that of all EU citizens

If you are a government official, a digital policy advisor, the CIO of a public administration, or a minister responsible for digital transformation in any EU country, this post is for you.

You do not need to invent a new policy, but to apply the logic you already accept (on sovereignty, interoperability, reducing dependence on suppliers, and building a public digital infrastructure that serves citizens rather than Big Tech shareholders) to the documents in your stack.

Germany has done so with determination. France, Italy and other countries have done so clearly, though not quite as resolutely. The European regulatory framework demands it, and the open-source ecosystem – with software that properly supports ODF, which today consists solely of solutions based on the LibreOffice Technology stack – is ready to support it.

The only thing standing between your administration and the ODF mandate is the decision to adopt it. We are ready to help you, not only to make this decision but also to turn it into a successful project.

The Document Foundation is the home of LibreOffice, and one of the leading advocates of open document standards in public administration across Europe and the world. For information on adopting LibreOffice and ODF in public administration, please write to info@documentfoundation.org.