Free content, multilingual online encyclopedia written and maintained by a community of volunteers through a model of open collaboration, using a wiki-based editing system.

Wikibase is the software that runs Wikidata, but is also usable for other projects beyond that. Wikibase allows the collaborative editing of structured data on top of MediaWiki. It is optimized for graph-like, schema-poor data, not for tabular and strongly pre-structured data.

Wiktionary is a multilingual, web-based project to create a free content dictionary, available in 158 languages. Unlike standard dictionaries, it is written collaboratively by volunteers, dubbed "Wiktionarians", using wiki software, allowing articles to be changed by...

Wikiquote is one of a family of wiki-based projects run by the Wikimedia Foundation, running on MediaWiki software. Based on an idea by Daniel Alston and implemented by Brion Vibber, the goal of the project, which began as an outgrowth to Wikipedia Famous Quotations, is to...

Wikinews is a free-content news source wiki and a project of the Wikimedia Foundation. The site works through collaborative journalism. Wikipedia co-founder Jimmy Wales has distinguished Wikinews from Wikipedia by saying "on Wikinews, each story is to be written as a news...

Wikisource is an online digital library of free content textual sources on a wiki, operated by the Wikimedia Foundation. Wikisource is the name of the project as a whole and the name for each instance of that project (each instance usually representing a different language);...

Wikibooks is a Wikimedia community for creating a free library of educational textbooks that anyone can edit.

Wikiversity is a Wikimedia Foundation project devoted to learning resources, learning projects, and research for use in all levels, types, and styles of education from pre-school to university, including professional training and informal learning.

Wikivoyage is a free web-based travel guide for travel destinations and travel topics written by volunteer authors. It is a sister project of Wikipedia and supported and hosted by the same non-profit Wikimedia Foundation.

Wikimedia Commons is a media file repository making available public domain and freely-licensed educational media content (images, sound and video clips) to everyone, in their own language.

Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species; the project is directed at scientists, rather than at the general public.

Wikidata is a free and open knowledge base that can be read and edited by both humans and machines.