Programming languages

There are many programming languages associated with MediaWiki, including:

PHP - the primary language that MediaWiki was originally written in, and which most new code in MediaWiki uses
JavaScript - language used for many important components of MediaWiki, notably VisualEditor, Parsoid, and all Gadgets, not to mention most code delivered to the browser via ResourceLoader for execution.
Lua - language of scripts executed via Scribunto.
Ruby - the base language for the browser test engine (Cucumber) and is used in Puppet deployment system.
Python - used in development of many tools such as Pywikibot.
Many client libraries available at API:Client code , including C++, C# (.NET), Java, OCaml, Objective-C, Perl, Python, R, and Ruby

Development guidelines
Policies	Development policy Architecture principles Services policy Support policy for PHP Gerrit/Privilege policy Stable interface policy MediaWiki database policy
General guidelines	Security for developers Performance guidelines Commit message guidelines Security checklist for developers Localisation Design style guide Documentation/Style guide Accessibility guide for developers Inclusive language Guidelines for a healthy code review culture Collaborative programming Best practices for extensions Pre-commit checklist
Code conventions	All languages PHP PHPUnit JavaScript CSS Selenium Lua Python Java SVG Vue Database schemas
API client code	Standards for API client libraries
Drafts	Code documentation

Coding Conventions