Wikimedia Hackathon Amsterdam 2013
www.mediawiki.org/wiki/Amsterdam_Hackathon_2013
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Wikimedia's annual development community meet-up the Wikimedia Hackathon will be held in Amsterdam, Netherlands in 2013 from 24-26 May. It is a long weekend filled with hacking anything related to MediaWiki or one of the Wikimedia projects (and sometimes other things, too). The Hackathon is completely open; we welcome both seasoned and new developers, as well as people working on MediaWiki, tools, pywikipedia, gadgets, extensions, templates, etc.