Jeroen De Dauw

Jeroen De Dauw
Software Craftsman

Wikidata & Wikibase

Wikidata is a free knowledge base that can be read and edited by humans and machines alike. It centralizes storage and management of Wikipedia's structured data and provides access to it in various open formats. It is powered by the Wikibase software, which is build on top of the MediaWiki platform and developed by Wikimedia Deutschland.

I was part of the original Wikidata team that started development of the software in 2012 and launched the website a year later. In 2019, I left Wikimedia Deutschland after being the Software Architect there for 6 years. During these years, I raked up over 6000 commits on the Wikibase software, nearly twice that of anyone else. You can find me in the contributors list on OpenHub.

Professional Wikibase Services

My company Professional Wiki provides professional Wikibase services including Wikibase software development, Wikibase cloud hosting, dedicated Wikibase hosting, and theming services.

We also run The Wikibase Consultancy.

Wikibase endorsements

Abraham Taherivand, Executive Director at Wikimedia Deutschland e. V.

"I had the pleasure to work with Jeroen at Wikimedia Deutschland. Jeroen is one of the most productive and passionate developers that I know. Without Jeroen, Wikidata would not have such a rich range of functions and would be built on a less flexible, lower-quality codebase and architecture. Jeroen has in-depth knowledge and broad experience about clean code and software architectures. I have always appreciated his professional attitude, collegial and reliable manner. He is an absolute win for any team and project!"

Denny Vrandečić, Wikidata Project Leader

"Jeroen is Technical Director at Professional.Wiki. Jeroen was working on Semantic MediaWiki and was one of the original developers on Wikibase at Wikimedia Deutschland. I had the pleasure of working with Jeroen for many years and have rarely found someone as dedicated as him towards the quality of the software he is working on."

Alaa Sarhan, Senior Engineer at Doodle

"Jeroen has been a key founding developer of Wikibase at Wikimedia Deutschland, where I had the pleasure to work with him at a later stage on that project. I have since appreciated his dedication to any project he works on, composed of his great understanding of first and advanced principles of software quality and evolution coupled with a pragmatic and business-oriented mindset."

Bernhard Krabina, Researcher at KDZ

"Jeroen is a very reliable and skilled developer. With Semantic MediaWiki, Wikibase and several other great MediaWiki extensions, such as Maps, ModernTimeline or Network, he is one of the most important contributors to these Open-Source-Projects. I will certainly continue working with him in the future."

Wikibase Software

Check out my Wikibase extensions.

I created several libraries part of the Wikibase software. These are used on websites such as Wikipedia and Wikidata and have received contributions from many other people.

Wikibase DataModel

The canonical PHP implementation of the Data Model at the heart of the Wikibase software.

Wikibase DataModel Serialization

Small library containing services to assist with serialization and deserialization of Wikibase DataModel objects.

Wikibase Internal Serialization

Services to assist with serialization and deserialization of Wikibase DataModel objects on the Wikimedia cluster.

Wikibase DataModel Services

A collection of services around Wikibase DataModel.

I also created these Wikibase related libraries:


Reading of, and iteration through, the Wikibase entities in a Wikibase Repository JSON dump.

Wikibase TermStore

Small library for looking up terms by item or property id or finding ids by term

QueryR EntityStore

Provides persistence and basic lookup capabilities for collections of Wikibase entities.

QueryR TermStore

Provides persistence of Wikibase terms with lookups of those terms and by those terms.


Note that the slides are generally not designed for after-talk usage. However, they are useful when watching the recording of a talk.

Wikibase: The Software behind Wikidata - slide preview

Abstract  •  Slides  •  Video  •  SMWCon Fall 2014

Blog posts

View my latest Wikibase blog posts

View older Wikidata blog posts

Use my expertise

You can contract me for development work, advise and training. Contact me at JeroenDeDauw[at]

MediaWiki hosting

Create your wiki today! Try out ProWiki via the free trial. Fully managed wiki hosting with instant setup and integrated admin panel.