Extension:SiteMatrix

The SiteMatrix extension adds a special page with a matrix of all sites of the Wikimedia Foundation. First a table of all normal language wikis, with blue links for existing wikis and red links for non-existing wikis. Below a list of other special projects (like Meta, Commons, Wikimania, ...), mostly the sites like.

Configuration
There are some variables that you need to change: You would also need to customise  to list the different wikis in your own wikifarm. To add a new site, follow the template in extension.json as a guide (but be sure to convert the syntax to PHP). However, you cannot remove any of the default sites (Wikipedia, Wiktionary, etc.) unless you edit extension.json directly, because extension loading does an 2D array merge.
 * - The path to a list of language codes recognised by MediaWiki (example).
 * - The path to a list of wiki databases that are private (optional)
 * - The path to a list of wiki databases that are public, but only logged in users can edit. (optional)
 * - The path of a list of wiki databases that "closed" (optional)

Additional requirements
To ensure that the extension works correctly to your needs, there are a few dependencies to this extension:
 * - To tell the extension all the wiki databases that exist in your wikifarm.
 * - To feed the extension with the correct links to the different wikis in your wikifarm.

API
This extension adds an API module that provides the same information as Special:SiteMatrix: a set of language groups plus special wikis.