The Wikimedia Foundation (WMF), founded June 2003, is the non-profit organization responsible for a very large number (over 850 in total) of very active wikis, grouped together and known as 'projects'; as well as the wiki engine software initially developed for them known as MediaWiki. The Foundations' wiki projects include Wikipedia (encyclopedias), Wiktionary (dictionary and thesaurus), Wikiquote (quotations), Wikibooks (open content textbooks), Wikinews (news source), Wikisource (free content primary and secondary source texts), Wikispecies (a free species directory), Wiktionary (dictionary), and many others as listed below. Most of these projects have separate wiki versions written in many different languages. There is also the Wikimedia Commons (for images, videos and other media files that can be used by all the Wikimedia projects), Wikidata (central space for data used on all WMF projects), and the Wikimedia Meta-Wiki (for issues common to all Wikimedia projects). Its most recent project, Wikivoyage (a 'travelpedia'), was added in late 2012.

Wikimedia Foundation is a member of the Open Source Initiative.

All Wikimedia Foundation projects and wikis (edit) • (category)

Wikipedia • Wiktionary • Wikibooks • Wikiquote • Wikisource • Wikispecies • Wikinews • Wikiversity • Wikivoyage • Commons • MediaWiki • Meta-Wiki • Incubator • Chapters • Wikimania • Outreach • Toolserver • Statistics • Wikitech • Strategic Planning • Labs • Downloads • Usability Initiative • Wikidata • Advisory Board • Spcom • Search Committee