UI/Theme Frameworks and Components

Ant Design	An enterprise-class UI design language and React-based implementation.
Balloon.css	Simple tooltips made of pure CSS
Bootflat	Open source Flat UI KIT based on Bootstrap
BootPress	A PHP Framework with a built in Blog and Flat File CMS
Bootstrap	Front-end framework for developing responsive, mobile first projects on the web
Bootswatch	Collection of free themes for Bootstrap
Cardinal	Small "mobile first" CSS framework for front-end developers who build responsive web applications
Flat UI Free	Theme and framework for Bootstrap
Fomantic-UI	The official community fork of Semantic-UI
Ink	set of tools for quick development of web interfaces
Metro UI CSS	Set of styles to create a site with an interface similar to Windows 8
Petal	A modern, light CSS UI framework developed at Shakr
Pre	CSS framework
prelude	Lightweight, responsive and extensible front-end framework
React Suite	🧱 A suite of React components
Schema	Light, responsive, and lean frontend UI framework
Semantic UI	UI component framework based around useful principles from natural language
Strapless	CSS boilerplate/framework for HTML elements, mixins library for patterns and color
UIkit	Lightweight and modular front-end framework for developing web interfaces
ngBoilerplate	An opinionated kickstarter for AngularJS projects
Wee	Lightweight front-end framework for logically building complex, responsive web projects

Grid Systems

Flexible Grid System
adaptGrid
Fluidable
Golden Grid System
Less Zen Grid
Order.less
responsibly
Responsive Boilerplate
Semantic.gs

Mixin Libraries

3L	Mixins library
animate	Library of CSS3 keyframe animations
Clearless	Collection of mixins
Css3LessPlease	Conversion of css3please.com to Less mixins
CssEffects	Collection of CSS style effects
Cssowl	Mixin library
cube.less	Animated 3D cube using only CSS
est	Mixin library
Hexagon	Generate CSS hexagons with custom size and color
homeless	Mixin library
LESS Elements	Set of mixins
LESS Hat	Mixins library
lessley	A jasmine like testing suite written in pure Less
Lessmore	Mixins library. Cross-browser support for the CSS3 features and more
LESS-bidi	Set of mixins for creating bi-directional styling
LESS-Mix	Mixins library
media-query-to-type	Media Queries to Media Types with Less
More-Colors.less	Variables for easier color manipulation while you design in the browser
more-less	Mixin lib supporting Less 1.7
More.less	Mixins, animations, shapes and more
more-or-less	for-loops and other functions + css3 mixins
normalize.less	Modularized famous normalize.css using Less
Oban	Collection of mixins
Preboot	Collection of variables and mixins. The precursor to Bootstrap
prelude-mixins	Collection of mixins
Shape.LESS	Collection of mixins for various shapes
tRRtoolbelt.less	Mixins and functions for common actions
Tuesday.less	CSS Animation mixins library
Less Style Library	A collection of variables and LESS namespaced mixins

Also see: GUIs for Less

Editors and IDEs

• Crunch 2! (built-in compiling, debugging, and searching across @imports)
• Mindscape Web Workbench (built-in support)
• NetBeans (built-in syntax highlighting)
• TextMate
• Vim
• Emacs
• JetBrains WebStorm, PhpStorm and other JetBrains IDEs (built-in support)
• Brackets (built-in syntax highlighting, several extensions for compilation)
• CodeLobster (built-in syntax highlighting)
• KineticWing IDE (built-in support)
• nodeMirror (built-in support, built-in HTML/CSS/Less preview)
• HTML-Kit Tools (built-in support)
• Dreamweaver CC (built-in support)

Sublime Text 2 & 3

• Less-sublime
• Sublime-Less-to-CSS
• Less-build-sublime
• SublimeOnSaveBuild

Eclipse

• Eclipse Less Plugin by Vincent Simonet
• Transpiler Plugin by Thomas Gossmann

Komodo Edit/IDE

• Komodo Less Compiler by Bob de Haas

Visual Studio

• CSS Is Less (Visual Studio)
• Web Essentials 2012 (Visual Studio 2012)
• Web Essentials 2013 (Visual Studio 2013)
• Web Tools 2013 (Visual Studio)

Dreamweaver

• DMXzone Less CSS Compiler

Notepad++ 6.x

• Less.js Syntax Highlighting User Defined Language by Raúl Salitrero
• Less.js Syntax Highlighting User Defined Language by azrafe7
• How to Install

Browser extensions

• Live editor for CSS and LESS - Magic CSS

Available Less plugins. Find more at GitHub and NPM Registry

Postprocessor/Feature Plugins

Autoprefixer	Add vendor prefixes
CSScomb	Beautify/format
clean-css	Compress/minify
CSSWring	Compress/minify
css-flip	Generate left-to-right (LTR) or right-to-left (RTL) CSS
functions	Write custom Less functions in Less itself
group-css-media-queries	Group CSS media queries
inline-urls	Convert url() to a call to data-uri()
lesshint	Lint your Less
lists	Lists/arrays manipulation (incl. loops)
pleeease	Postprocess using pleeease
rtl	Reverse from ltr to rtl
variables-output	Export top-level variables to a JSON file

Preprocessors

sass2less	Import and convert Sass/SCSS files into your Less code (incl. variables, mixins and more)

Import Plugins

bower-resolve	Import from a Bower package
glob	Globbing support in Less imports
npm-import	Import from npm packages
resolve-blocks	Going up a tree to find specified component

Function Libraries

advanced-color-functions	Functions to find more contrast colors
cubehelix	A cubehelix function
lists	Lists/arrays manipulation functions
urlencode	URL Encode function
util	A set of utility functions

Framework Importers

Bootstrap	Bootstrap
Cardinal	Cardinal
Flexbox Grid	Flexbox Grid
Flexible Grid System	Flexible Grid System
Ionic	Ionic
Lesshat	Lesshat
Skeleton	Skeleton

Tip: try out the different Less tools available for your platform to see which one meets your needs.

This page focuses on GUI compilers. For command line usage and tools see Command Line Usage.

Cross platform

Crunch 2!

The editor and compiler for awesome people.

Crunch 2 is a cross-platform (Windows, Mac, and Linux) editor with integrated compiling. If you work with large Less projects, you should definitely try it out, as you only need the free version for Less files. Available at: https://getcrunch.co/.

Koala

Koala is a cross-platform GUI application for compiling less, sass and coffeescript.

Features: cross platform, compile error notification supports and compile options supports.

Get more info: http://koala-app.com/

Prepros

Prepros is a tool to compile Less, Sass, Compass, Stylus, Jade and much more.

Get more info at https://prepros.io/

Specific platforms

Windows

WinLess

WinLess started out as a clone of Less.app, it takes a more feature-complete approach and has several settings. It also supports starting with command line arguments.

Get more info: http://winless.org

OS X

CodeKit

CodeKit is the successor to LESS.app, and supports Less among many other preprocessing languages, such as SASS, Jade, Markdown, and many more.

Get more info: http://incident57.com/codekit

LiveReload

CSS edits and image changes apply live. CoffeeScript, SASS, Less and others just work.

Get more info: http://livereload.com

Linux

Plessc

Plessc is a gui fronted made with PyQT.

Auto compile, log viewer, open the less file with the editor chosen, settings for compile the file. Get more info: https://github.com/Mte90/Plessc

less2css.org	Online Integrated Development Environment (IDE) that is hosted in a browser allowing users to edit and compile Less to CSS in real-time.
winless.org/online-less-compiler	This Online Less Compiler can help you to learn Less. You can go through the examples below or try your own Less code.
lesstester.com	Online compiler for Less CSS.
leafo.net/lessphp/editor	lessphp live demo.
estFiddle	Online Less compiler providing live demo for Less and est. Allowing users to switch among all versions of Less after 1.4.0 with optional est/Autoprefixer functionalities.
BeautifyTools Less Compiler	Online Less compiler with optional formatting and minification at BeautifyTools
Less WebCompiler	The most configurable Less web compiler on the internet, it allows to render the CSS output with your own Coding Standards!

Online Web IDEs/Playgrounds with Less support

CSSDeck Labs	CSSDeck Labs is a place where you can quickly create some experiments (or testcases) that involves HTML, CSS, JS code.
CodePen	CodePen is a playground for the front end side of the web.
Fiddle Salad	An online playground with an instantly ready coding environment.
JS Bin	JS Bin is a webapp specifically designed to help JavaScript and CSS folk test snippets of code.
jsFiddle	Online Web Editor

Node.js Tools

• grunt-contrib-less
• gulp-less: Please note that this plugin discards source-map options, opting to instead using the gulp-sourcemaps library.
• svelte-preprocess: (converts Less to CSS before passing it to the Svelte compiler)
• Connect Middleware for Less: Connect Middleware for Less compiling

Other Technologies

Wro4j Runner CLI Download the wro4j-runner.jar file and run the following command:

java -jar wro4j-runner-1.5.0-jar-with-dependencies.jar --preProcessors lessCss

More details can be found here: Wro4j Runner CLI

CSS::LESSp

http://search.cpan.org/~drinchev/CSS-LESSp/

lessp.pl styles.less > styles.css

Windows Script Host

Note - the official Less node runs on windows, so we are not sure why you would use this.

Less.js for Windows with this usage:

cscript //nologo lessc.wsf input.less [output.css] [-compress]

or

lessc input.less [output.css] [-compress]

dotless

dotless for Windows can be run like this:

dotless.Compiler.exe [-switches] <inputfile> [outputfile]

Also see:

• Ports of Less

Java

• Lesscss (Runs less.js using Rhino, Nasshorn or node.js engine; 1.7.0 compliant)
• Lesscss gradle plugin (Gradle plugin based on Lesscss)
• Less Engine (Runs less.js in the Rhino JVM-based JavaScript interpreter)
• Less CSS Compiler for Java (Runs less.js in the Rhino JVM-based JavaScript interpreter)
• Less4j (Native Java implementation.)
• JLessC (Less compiler written completely in Java)

.Net

• Less CSS for .Net
• BundleTransformer.Less

PHP

• lessphp
• BW Less CSS (WordPress Plugin)
• less.php
• ILess

Python

• Python Less Compiler

Ruby

• Less.js In Ruby's V8 Engine

Go

• Less.js In Go (Runs less.js inside embedded Javascript engine)

Know of another port that should be added to this list? Please let us know.