Year: 2026

In LibreOffice development, there are many cases where you want to validate some documents against standards: either Open Document Format (ODF) or MS Office Open XML (OOXML). Here I discuss how to do that.

Open Document Format (ODF) Validation

ODF is the native document file format that LibreOffice and many other open source applications use. It is basically set of XML files that are zipped together, and can describe various aspects of the document, from the content itself to the way it should be displayed. These XML files have to conform to ODF standard, which is presented in XML schemas. The latest version of ODF is 1.4, which is yet to be implemented in LibreOffice.

You can find more about ODF in these links:

• Wikipedia – OpenDocument
• Open Document Format for Office Applications (OpenDocument) TC

There are various tools to do the validation, but the preferred one is the ODF Toolkit Validator:

• ODF Toolkit website > ODF Validator 
• ODF Toolkit on Github

Compiled binaries of ODF Toolkit can be downloaded from the above Github project:

• odftoolkit-0.12.0-bin.zip

Then, you can use the ODF validator this way:

$ java -jar odfvalidator-0.12.0-jar-with-dependencies.jar test.odt

You may also use the online validator, odfvalidator.org, to do a validation.

Please read this disclaimer before using:

This service does not cover all conformance criteria of the OpenDocument Format specification. It is not applicable for formal validation proof. Problems reported by this service only indicate that a document may not conform to the specification. It must not be concluded from errors that are reported that the document does not conform to the specification without further investigation of the error report, and it must not be concluded from the absence of error reports that the OpenDocument Format document conforms to the OpenDocument Format specification.

Office Open XML (OOXML) Validation

MS Office Open XML (OOXML) is the native standard for Microsoft documents format. It is also a set of XML files zipped together, and conform to some XML schemas.

You can find out more about OOXML here:

• Wikipedia – Office Open XML

There are tools to do the validation, and the one is used in LibreOffice is Office-o-tron. One can use it with below command to validate an example file, test.docx:

$ java -jar officeotron-0.8.8.jar ~/test.docx

Office-o-tron can be downloaded from dev-www.libreoffice.org server of LibreOffice, and this is currently the latest version:

• Office-o-tron 0.8.8 Jar file

It is worth noting that Office-o-tron can be also used to validate ODT files.

Extensions to ODF Standard

To go beyond the current ODF standard, new features are sometimes introduced as “ODF extensions”, then are gradually added to the standard. You can read more in TDF Wiki:

• ODF > ODF Extensions > Why does LibreOffice save extended ODF by default?

In these cases, you may see validation errors for such extensions. For example:

test.odt/styles.xml[2,3347]: Error: unexpected attribute “loext:tab-stop-distance”
test.odt/styles.xml[2,4849]: Error: unexpected attribute “loext:opacity”

You may avoid such errors by using -e option, which ignores such unknown markups:

-e: Check extended conformance (ODF 1.2 and 1.3 documents only)

If you want ODF 1.4 support and other new features in ODF validator, you need to build ODF Toolkit from source. You can then run it with this command:

$ java -jar ./validator/target/odfvalidator-0.13.0-SNAPSHOT-jar-with-dependencies.jar test.odt

The plan from ODF Toolkit developers is to publish a new release. I hope that happens soon.

Final Words

When you want to make sure that the ODT or OOXML document you generate is valid according to the standards, then you need validation. Sometimes, it is the opposite: you want to make sure that the input document is valid before processing it, or when you want to know if the problem is from LibreOffice (or other processors), or the document itself. Then, again, the validator is the right tool to use.