Frontend Developer Wikidata (m/f) freelancer/contractor

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Wikimedia Deutschland – Gesellschaft zur Förderung Freien Wissens e. V. is a non-profit organisation based in Berlin, Germany. With more than 85 employees and about 50.000 members, it is the oldest and largest of more than 40 independent chapters of the international Wikimedia movement. The most well-known Wikimedia project, the free online encyclopedia Wikipedia, is used by millions of people across the world every day and is continuously updated and improved by millions of users.

In the software development department of Wikimedia Deutschland e.V. we are building open source software that impacts the world. One of the main projects of the department is Wikidata, a free and open knowledge base containing general-purpose data about the world. Wikidata is Wikimedia’s central data repository. It is the building block of Wikimedia’s and Wikipedia’s future. Wikidata’s community and development team are working every day to give more people more access to more knowledge.

All software we develop is open source, and we also contribute back to various projects we use. Many of our components are published in a form that allows reuse outside of our own projects.

As a Frontend Developer you will work primarily on the user interface parts of Wikibase, the software behind Wikidata, and its integration into other Wikimedia projects. We are looking for someone to join the Wikidata team working in our office in the heart of Berlin, though working remotely is an option, too.


About you:

  • You care about coding; you have a passion which you can clearly convey by your actions rather than personal statements on your CV
  • You have an eye for good software design and you know how to assure high quality
  • You can recognize legacy code and know how to effectively deal with it
  • You are able to communicate fluently in English as part of a multidisciplinary team
  • For you it’s more than a job


The Wikidata team is cross-functional, self organizing and highly autonomous. You’ll be working directly with the Product Owner and be able to interact with various stakeholders in the community.


Among other things, testing, refactoring, and pair programming are encouraged. We’re constantly trying to improve the way we work:

  • We have internal presentations by our developers on topics they are enthusiastic about
  • You can attend local user groups during working time and we regularly visit conferences, both as attendees and presenters
  • You will have a noticeable impact on one of the sixth most visited websites in the world: Wikipedia.


Wikibase is an extension to the MediaWiki framework and the frontend parts are mainly written in JavaScript interacting with server side PHP code. We’re interested in candidates from any background, as long as you have a solid understanding of Object Oriented languages and good experience with state-of-the-art web development.


Here is an (incomplete) list of technologies we currently use:

  • JavaScript, PHP
  • MediaWiki, several MediaWiki extensions
  • PHPUnit, QUnit, Cucumber, Selenium, PHPCS, PHPMD, JSLint
  • Git, Gerrit
  • MySQL, SQLite
  • Composer
  • TravisCI, ScrutinizerCI


To begin your application, please answer the questions and complete the exercises at https://www.hackerrank.com/tests/gite1kil0a4/0a461b5e75c2384c5775ee19ad67e586. If the results are satisfactory, we will be in touch. When you have any questions please contact sandra.muellrick@wikimedia.de

Additionally you can find all information about Jobs & Products of the WMDE Software Development and Engineering Department in english here: https://software.wikimedia.de/


Wikimedia Deutschland commits itself to the principles of equal opportunity and does not discriminate on the basis of ethnic origin, nationality, religion, political or other opinion, gender, age, disability or sexual identity or orientation.