A module wrapper for Wikimedia’s Less parser that compiles .less files to .css. Also used by the ProcessWire core for AdminThemeUikit customization.

Less parser for ProcessWire

This is a ProcessWire module wrapper for the Wikimedia LESS parser. Originally developed by Bernhard Baumrock with additions by Ryan Cramer. Requires ProcessWire 3.0.164+.


  • ProcessWire 3.0.179 or newer (3.0.229+ preferable)
  • PHP 7.4 or newer


  1. Copy all files included in this module into new directory /site/modules/Less/.
  2. In the ProcessWire admin, go to Modules > Refresh.
  3. Click install for the Less module.

API usage

Compile string and two .less files to a css file

$less = $modules->get('Less');
$less->setOption('compress', true);
$less->addStr('@color: #4D926F; h2 { color: @color; }');
$less->addFile('/path/to/file2.less', '/url/to/images/');

Access Wikimedia less parser directly

$parser = $less->parser();
$css = $parser->getCss();

For details about API methods you can access from $parser see: https://github.com/wikimedia/less.php/blob/v4.1.1/API.md

Usage with ProcessWire’s AdminThemeUikit module

Install this module to add the ability to customize the ProcessWire core AdminThemeUikit admin theme module CSS. For this usage, you must have ProcessWire 3.0.179 or newer. See instructions here: https://processwire.com/blog/posts/pw-3.0.179/


This module uses the Apache license for consistency with the Wikimedia LESS parser license.

Install and use modules at your own risk. Always have a site and database backup before installing new modules.

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