New Developers/Introduction to the Wikimedia Technical Ecosystem

This page provides an overview of Wikimedia software and infrastructure for new technical contributors. Its goal is to help developers understand the major areas where you can apply your technical skills to help support and grow the Movement.

Open source
The Wikimedia technical ecosystem is guided by free and open source software (FLOSS) principles. Contributors around the world volunteer their time to maintain and extend the technology behind Wikimedia projects. This means that the Wikimedia technical ecosystem consists of many unique projects with varying contributing guidelines, design patterns, hosting locations, and code review processes.

Open source values like shared ownership and strong privacy commitments are central to Wikimedia's technical infrastructure, software, and services. For example:


 * For version control and code review, the Wikimedia Foundation (WMF) uses Git and Gerrit. Git is a free and open source distributed version control system, and Gerrit is a free, web-based collaborative code review tool that integrates with Git.
 * Wikimedia Cloud Services (WMCS) provides cloud computing infrastructure, shared hosting (platform as a service), and data services for contributors to Wikimedia software projects. You can use these services to host your software tools for the Wikimedia movement, for free, instead of using proprietary, paid, or non-open-source services.

In addition to providing tools and services for technical contributors, WMF maintains core infrastructure like data centers, search, networking, and global traffic routing. You don't need to learn about those in order to contribute to wiki projects, but you should know about the core software that powers Wikipedia and other wikis: MediaWiki.

MediaWiki
Wikimedia projects, including Wikipedia, run on the MediaWiki software platform. MediaWiki is free and open source software, built specifically for collecting and organizing free and open knowledge. It's multilingual, extensible, customizable, and reliable. MediaWiki enables users around the world to edit, organize, maintain, and collaborate on wikis. It manages the display of content like text, photos, formatting, and revisions. MediaWiki is more than just a content management system: it also provides tools to handle spam and vandalism, and other functionality that supports community curation of freely-reusable knowledge on an open platform.

MediaWiki core and extensions
The MediaWiki software is developed collaboratively by people from all around the world. The Wikimedia technical community has added many key features to MediaWiki and built a large ecosystem of extensions to the core software. Due to its complexity, contributing to MediaWiki may be more challenging than other types of technical contributions. As a new contributor, focus on features and bugs that only touch a small region of code. Avoid building new MediaWiki skins and extensions: every new extension adds to the software's overall maintenance burden, and can block the launch of new, crucial features. Instead, look into working on one of the many existing extensions.

To learn more, visit How to become a MediaWiki hacker.

Wikimedia mobile apps
Mobile apps expand the reach of Wikimedia content by allowing users to interact with Wikimedia without using a browser. There are apps for the Android, iOS, and KaiOS platforms, apps for different Wikimedia projects like Commons, Wikipedia, and Wiktionary, and apps for activities like reading, contributing, and more. Many apps have vibrant developer communities and welcome new contributors.

To learn more, visit Wikimedia Apps.

Templates and modules
Templates enable one piece of content to appear on multiple wiki pages ("transclusion"). Many wikis rely heavily on templates: there are thousands of them, they're used on almost every page, and they're integral to wiki functionality. You can pass parameters to templates to customize how content is handled in different contexts.

You don't need a developer account to edit or create a template, and they're written in wikitext. That makes templates an easy way to get started with customizing wiki behavior.

Modules are similar to templates, but instead of being written in wikitext, they use the Lua programming language.  While templates are part of the core MediaWiki application, support for modules is implemented by an extension called Scribunto.

To learn more about templates, visit Help:Templates. To learn more about modules and how Lua is used on MediaWiki, visit the Scribunto Lua manual.

User scripts and gadgets
MediaWiki supports front-end customization, or "on-wiki" development, to enhance the software's core functionality. User scripts are Javascript and/or CSS that provide additional features on top of MediaWiki. Code lives on the wiki, and is injected from the client side on MediaWiki via user preferences. You can modify your local Javascript and CSS to change the appearance and behavior of your own interface. Individual users can add features for themselves as long as they follow expectations and guidelines around doing so. If you build something that others can use, you can share your scripts informally, or work with a wiki community to investigate making your customizations available to other users and projects as a "gadget".

Gadgets are user-generated customizations that are available for installation on a wiki, via the Gadgets MediaWiki extension. Many gadgets originated as user scripts that became widely-used on their home wiki, and admins wanted to make them easier for everyone to find and use. Admins can configure which gadgets are available and enabled by default for an entire MediaWiki site or skin.

To learn more about user scripts and gadgets, visit "Gadget kitchen".

Build tools and bots to help Wikimedia projects
MediaWiki APIs provide direct access to the data contained in the MediaWiki database. This includes wiki content, metadata, analytics data, and more. You can use these APIs to build apps that contribute content or new functionality to the Wikimedia ecosystem. The API modules provide programmatic access to much of the same functionality provided by the MediaWiki web interface.

Bots
Bots are automated programs that help wiki projects by doing crucial but repetitive tasks. Bots save human effort by correcting missing or extra spaces, suggesting articles to newcomers, fixing broken links, and more. Bot automation supports Wikimedia volunteers by allowing them to spend more of their time on tasks that require human intelligence, like writing articles, finding sources, fact checking, and synthesizing multiple points of view.

Bots can request pages and submit edits to wikis just like how human users do the same tasks in a web browser. Because bots access pages the same way people do, they can get caught in edit conflicts, have page timeouts, or run across other unexpected complications while requesting pages or making edits. Since bots generally complete high-volume work, you should consider these situations when writing a bot.

To learn more about bots, visit Manual:Creating a bot.

Tools
Tools are software applications that help people working on Wikimedia projects. Tools can do all kinds of tasks, like help editors discover content to improve, simplify edit-a-thon planning, visualize wiki content, help fight vandalism, and much more.

The MediaWiki Action API gives you programmatic access to content on any Wikimedia wiki. You can use the Action API to search and display wiki pages, get media files, edit pages, and manage wikis. Client libraries implementing the MediaWiki API are available in many languages, including Python and JavaScript.

To explore more Wikimedia tools, visit Toolhub.

Join the Wikimedia tech community
A great way to find ways to contribute is to get connected to the technical community. You can meet people and discuss development work on various communication channels and at events like Hackathons. The Wikimedia Foundation also offers outreach programs to mentor new developers.

Get started as a new contributor

 * Visit the New Developers page to learn more about getting started with development and contributing to Wikimedia open source.
 * Use the Developer Portal to find curated resources and tutorials for your area of interest.