Manual:Extensions

Extensions:

An extension lets you customise how MediaWiki looks and works.

Wiki users can browse through extensions.
System administrators can install (or remove) extensions on the MediaWiki installations that they manage.
Developers can write new extensions or improve or maintain extensions.

While some extensions are maintained by MediaWiki developers, others were written by third-party developers. As a result, many have bugs, and they are not all guaranteed to be compatible with each other. Some are unmaintained; not all extensions work on all versions of MediaWiki. Use any extension, especially those tagged as insecure, at your own risk. If you are using an extension that requires patches to the core software, be sure to back up your database. This helps avoid the risk of breaking your wiki.

Types of extensions

Parser tags

Parser tags extend the built-in wiki markup with additional capabilities, whether simple string processing, or full-blown information retrieval.

Parser functions

Parser functions are special wiki markup syntax that can 'interact' with other wiki elements in the page, and give a specific output.

Hooks

Hooks allow custom code to be executed when some defined event (such as saving a page or a user logging in) occurs.

Special pages

Special pages are pages that are created by the software on demand to perform a specific function.

Skins

Skins allow users to customise the look and feel of MediaWiki.

Magic words

Magic words are a technique for mapping a variety of wiki text strings to a single ID that is associated with a function.

API

MediaWiki provides an action API, a web service that allows access to some wiki-features like authentication, page operations, and search.

Page content models

The ContentHandler introduced in MediaWiki 1.21 makes it possible for wiki pages to be composed of data other than wikitext, such as JSON or Markdown.

Authentication

MediaWiki provides SessionManager and AuthManager, two authentication-related frameworks to enhance security via custom authentication mechanisms.

Finding extensions

Browsing extensions

You can browse Category:Extensions by category to see the full range of extensions that have already been written. For information on installing these extensions or writing your own, see below.

Checking installed extensions

Only someone with administration access to the filesystem (and often the database too) on a server can install extensions for MediaWiki, but anyone can check which extensions are active on an instance of MediaWiki by accessing the Special:Version page. For example, these extensions are active in the English Wikipedia.

Popular extensions

There are a number of ways of finding popular extensions.

The first set is those that are bundled with MediaWiki (a list that is reviewed regularly, and to which anyone can suggest an addition).

Extensions that are downloaded from MediaWiki.org via the ExtensionDistributor mechanism have some statistics gathered. The top 15 most downloaded extensions are listed at Special:ExtensionDistributor, and applicable extensions have their download count shown in their infobox. Note that these numbers do not account for alternate ways of installing extensions, such as via Git or Composer.

A third option is to look at WikiApiary 's counts of wikis that extensions are installed on. This has the advantage of representing actual installations and not just downloads (i.e. it queries the wiki's APIs), but it is also (as of 2023) not completely up to date. It also doesn't count installations on private wikis.

Installing an extension

For further guidance, see also Manual:Extensions/Installation and upgrade

MediaWiki is ready to accept extensions just after installation is finished. To add an extension follow these steps:

Before you start
Many extensions provide instructions designed for installation using Unix commands. You require shell access (SSH) to enter these commands listed on the extension help pages.
Download your extension.
Extension Distributor helps you to select and download most of the popular extensions.

Extensions are usually distributed as modular packages. They generally go in their own subdirectory of $IP /extensions/. A list of extensions stored in the Wikimedia Git repository is located at git:mediawiki/extensions. Some extensions don't use version control and are not recommended.

Some extensions are also available in bundles, composer or package repositories.

It's recommended to read the README file before installation. It usually contains important info about configuration.
Install your extension.
At the end of the LocalSettings.php file, add:
```
wfLoadExtension( 'ExtensionName' );
```
This line forces the PHP interpreter to read the extension file, and thereby make it accessible to MediaWiki.

Some extensions can conflict with maintenance scripts, for example if they directly access $_SERVER (not recommended).

In this case they can be wrapped in the conditional so maintenance scripts can still run.
```
if ( !$wgCommandLineMode ) {
   wfLoadExtension ( 'ExtensionName' );
}
```
The maintenance script importDump.php will fail for any extension which requires customised namespaces which is included inside the conditional above such as Extension:Semantic MediaWiki , Extension:Page Forms .

Ensure that required permissions are set for extensions!

While this installation procedure is sufficient for most extensions, some require a different installation procedure. Check your extension's documentation for details.

If you want to alter configuration variables in LocalSettings.php, you have to do this typically after including the extension. Otherwise defaults defined in the extension will overwrite your settings.

Upgrading an extension

Some extensions require to be updated whenever you update MediaWiki, while others work with multiple versions. To upgrade to a new version of an extension:

Download the new version of the extension
Replace all the extension files in the extensions/ExtensionName directory with the new files. Do not remove the extension configuration present in LocalSettings.php
If the extension requires changes to the MediaWiki database, you will need to run the update.php maintenance script. Most extensions will mention if this script needs to be run or not. (Perform backup of your data before executing the script). If you don't have command line access, you can also use the web updater.

These instructions cover 99% of extensions. If the specific extension you are upgrading has instructions that differ from these, you should probably follow the specific extension's instructions

Uninstalling an extension

Remove the line from LocalSettings.php with the extension name to uninstall it:

wfLoadExtension( 'ExtensionName' );

You must remove any lines pertaining to the configuration of the extension.