Fandom

Wikia is a free web hosting service that uses a fork of MediaWiki as its hosting engine and is known for its wide variety of MediaWiki extensions. See Wikia's website or the Wikipedia article on Wikia to find out more about Wikia in general.

Source Code
Wikia's Git repository can be accessed at github.com/wikia/app. Please note that it is an entirely separate repository from Wikimedia's official Git repository and is not affiliated with the official Git.

The Wikia's SVN repository still is available at svn.wikia-code.com and their Trac browser although [http://dev.wikia.com/wiki/User_blog:Relwell/Wikia_is_moving_to_GitHub! these are now unmaintained].

Extensions
Some of Wikia's extensions can be found at Wikimedia's official Git repository and their appropriate extension pages are located at Category:Extensions by Wikia, Inc.

Other extensions are still located in Wikia's own Git repository, in the folder /extensions/wikia/. It is likely that most of the extensions have dependency on Nirvana (found at /includes/wikia/nirvana), the EasyTemplate class (found at /includes/wikia/ folder on Wikia's Git) and/or they might require custom database tables.

Source code comments are not as common as in the official MediaWiki either.