OOUI

OOUI allows to rapidly create responsive web user-interfaces and applications. It operates consistently across a multitude of browsers and is internationalization and accessibility ready.

The OOUI library contains
 * ready-to-use widgets, layouts, and windows that can be instantiated directly or easily extended,
 * a PHP server-side compatible output for cases where JavaScript is not supported,
 * elements that can be easily mixed and matched to create custom user interfaces.

OOUI is available in MediaWiki Core, as well as on npm, Composer, and through cdnjs. OOUI implements a "WikimediaUI" theme – conforming to Wikimedia Foundation's design style guide. Interfaces built within MediaWiki use this theme by default, though different MediaWiki skins can and do over-ride this. See documentation about using OOUI in MediaWiki.

Note, that the library was originally created for use by VisualEditor, which uses it for its entire user interface, on top of the OOjs primer (Object-Oriented JavaScript, hence OOUI's former name "OOjs UI") and has been later extended to serve MediaWiki Core with PHP implemented widgets.

The source code is hosted on Gerrit.