Jeroen De Dauw

Jeroen De Dauw
Software Craftsman

My open source projects



Most of my open source work is related to MediaWiki, Semantic MediaWiki or Wikidata.

Wikimedia Deutschland fundraising application

Wikimedia Deutschland fundraising

After leading the creation of this application, I have written and spoken multiple times about its architecture.

PHP libraries


Small library for representing, computing and applying diffs between structured data. Used by Wikipedia.

DataValues Geo

Small library for parsing, formatting and representing coordinates. Used by Wikipedia.

File Fetcher

Tiny library providing an OO file_get_contents alternative, including adapters and decorators.


Test Doubles for the PSR-3 Logger Interface.


Processes parameters in declarative fashion. Written in 2010 so contains a lot of legacy code.

Simple Cache

Tiny library defining a minimalistic caching interface and provides some basic implementations.


PHP value object for representing a positive amount of Euro.


Tiny library defining interfaces for services that assist with serilization and deserialization.

Batching Iterator

Tiny library providing an Iterator that batches requests for additional values.

Message Reporter

Tiny library defining an interface to report arbitrary text messages.


Extended Date/Time Format implementation created in 2021 for the Luxembourg Ministry of Culture.


Micro library with PostRequestSender interface and some test doubles.

Wikibase libraries

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.

Supreme Commander maps

I maintain several survival maps (custom scenarios written in Lua) for Supreme Commander Forged Alliance Forever. These maps were created long ago by other people, and I have been gradually cleaning up their code and adding features.

Historical projects

  • QueryR API - a REST compliant webservice for accessing information stored in Wikidata written during 2014 and 2015 in PHP
  • ReplicatoR - a CLI application to replicate Wikibase entities (mainly from Wikidata) written during 2014 and 2015 in PHP
  • Skynet - Travelling Salesman Problem solving application (using GALib) written during 2010 in C#
  • GALib - Genetic Algorithm library written during 2010 in C#
  • BN+ Converter Pro - A desktop application providing various text conversion utilities written between 2007 and 2010 in VB.Net
  • BN+ Brute Force Hash Attacker - A tool for brute forcing hashes written between 2008 and 2010 in VB.Net
  • BN+ Library - A .Net utilities library written between 2008 and 2010 in Visual Basic .Net
  • Art of Defence SE4 - A Command and Conquer: Generals custom map created between 2008 and 2010
  • These libraries in C# and VB.Net (external link)

See also

Use my expertise

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