diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..82bde64
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+node_modules/
+coverage/
+.nyc_output/
+yarn.lock
+package-lock.json
\ No newline at end of file
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..47b3eaa
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,11 @@
+language: node_js
+node_js:
+  - 'node'
+  - '10'
+  - '8'
+os:
+  - windows
+  - linux
+  - osx
+after_success:
+  - 'npm run coveralls'
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..235d03c
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,11 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [1.0.0] - 2017-08-22
+
+### Added
+
+- Everything
\ No newline at end of file
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..4a74f3b
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2019 Dennis Schad
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..31499e0
--- /dev/null
+++ b/README.md
@@ -0,0 +1,56 @@
+# rosid-handler-less
+
+[![Travis Build Status](https://travis-ci.org/freedeebee/rosid-handler-less.svg?branch=master)](https://travis-ci.org/freedeebee/rosid-handler-less) [![Coverage Status](https://coveralls.io/repos/github/freedeebee/rosid-handler-less/badge.svg?branch=master)](https://coveralls.io/github/freedeebee/rosid-handler-less?branch=master) [![Dependencies](https://david-dm.org/freedeebee/rosid-handler-less.svg)](https://david-dm.org/freedeebee/rosid-handler-less#info=dependencies) [![Greenkeeper badge](https://badges.greenkeeper.io/freedeebee/rosid-handler-less.svg)](https://greenkeeper.io/)
+
+A function that loads a LESS file, transforms it to CSS, adds vendor prefixes and minifies the output.
+
+## Install
+
+```
+npm install rosid-handler-less
+```
+
+## Usage
+
+### API
+
+```js
+const handler = require('rosid-handler-less')
+
+handler('main.less').then((data) => {})
+handler('main.css', { optimize: true }).then((data) => {})
+```
+
+### Rosid
+
+Add the following object to your `rosidfile.json`, `rosidfile.js` or [routes array](https://github.com/electerious/Rosid/blob/master/docs/Routes.md). `rosid-handler-less` will transform all matching LESS files in your source folder to CSS.
+
+```json
+{
+  "name"    : "LESS",
+  "path"    : "[^_]*.{css,less}*",
+  "handler" : "rosid-handler-less"
+}
+```
+
+```less
+/* main.less */
+.class {
+  color: white;
+}
+```
+
+```css
+/* main.css (output) */
+.class { color: white; }
+```
+
+## Parameters
+
+- `filePath` `{String}` Absolute path to file.
+- `opts` `{?Object}` Options.
+	- `optimize` `{?Boolean}` - Optimize output. Defaults to `false`.
+
+## Returns
+
+- `{Promise<String|Buffer>}` The transformed file content.
\ No newline at end of file
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..c6f3771
--- /dev/null
+++ b/package.json
@@ -0,0 +1,48 @@
+{
+  "name": "rosid-handler-less",
+  "version": "1.0.0",
+  "authors": [
+    "Dennis Schad <dennis.schad1991@gmail.com>"
+  ],
+  "description": "Load LESS and transform to CSS, add vendor prefixes and minify",
+  "main": "src/index.js",
+  "keywords": [
+    "rosid",
+    "handler",
+    "transform",
+    "compile",
+    "less",
+    "postcss",
+    "autoprefixer",
+    "cssnano"
+  ],
+  "license": "MIT",
+  "homepage": "https://github.com/freedeebee/rosid-handler-less",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/freedeebee/rosid-handler-less.git"
+  },
+  "files": [
+    "src"
+  ],
+  "scripts": {
+    "coveralls": "nyc report --reporter=text-lcov | coveralls",
+    "test": "nyc node_modules/mocha/bin/_mocha"
+  },
+  "dependencies": {
+    "autoprefixer": "^9.4.8",
+    "cssnano": "^4.1.10",
+    "less": "^3.10.2",
+    "postcss": "^7.0.14"
+  },
+  "devDependencies": {
+    "chai": "^4.2.0",
+    "coveralls": "^3.0.3",
+    "fsify": "^3.0.0",
+    "mocha": "^6.0.0",
+    "nyc": "^14.0.0"
+  },
+  "mocha": {
+    "timeout": "100000"
+  }
+}
diff --git a/src/index.js b/src/index.js
new file mode 100644
index 0000000..5e70ca2
--- /dev/null
+++ b/src/index.js
@@ -0,0 +1,69 @@
+'use strict'
+
+const util = require('util')
+const path = require('path')
+const fs = require('fs')
+const less = require('./less')
+const postcss = require('./postcss')
+
+/**
+ * Load LESS and transform to CSS, add vendor prefixes and minify.
+ * @public
+ * @param {String} filePath - Absolute path to file.
+ * @param {?Object} opts - Options.
+ * @returns {Promise<String>} CSS.
+ */
+module.exports = async function(filePath, opts = {}) {
+
+	if (typeof filePath !== 'string') throw new Error(`'filePath' must be a string`)
+	if (typeof opts !== 'object') throw new Error(`'opts' must be undefined or an object`)
+
+	const folderPath = path.dirname(filePath)
+
+	opts = Object.assign({
+		optimize: false
+	}, opts)
+
+	let output = null
+
+	output = await util.promisify(fs.readFile)(filePath, 'utf8')
+	output = await less(folderPath, output, opts)
+	output = await postcss(filePath, output, opts)
+
+	return output
+
+}
+
+/**
+ * Tell Rosid with which file extension it should load the file.
+ * @public
+ * @param {?Object} opts - Options.
+ * @returns {String} File extension.
+ */
+module.exports.in = function(opts) {
+
+	return (opts != null && opts.in != null) ? opts.in : '.less'
+
+}
+
+/**
+ * Tell Rosid with which file extension it should save the file.
+ * @public
+ * @param {?Object} opts - Options.
+ * @returns {String} File extension.
+ */
+module.exports.out = function(opts) {
+
+	return (opts != null && opts.out != null) ? opts.out : '.css'
+
+}
+
+/**
+ * Attach an array to the function, which contains a list of
+ * file patterns used by the handler. The array will be used by Rosid for caching purposes.
+ * @public
+ */
+module.exports.cache = [
+	'**/*.less',
+	'**/*.css'
+]
\ No newline at end of file
diff --git a/src/less.js b/src/less.js
new file mode 100644
index 0000000..1bdbd6b
--- /dev/null
+++ b/src/less.js
@@ -0,0 +1,31 @@
+'use strict'
+
+const util = require('util')
+const less = require('less')
+
+/**
+ * Transform LESS to CSS.
+ * @public
+ * @param {String} folderPath - Path to the folder containing the LESS file.
+ * @param {String} str - LESS.
+ * @param {Object} opts - Optional options for the task.
+ * @returns {Promise<String>} CSS.
+ */
+module.exports = async function(folderPath, str, opts) {
+
+	// LESS can't handle empty files
+	if (str === '') return str
+
+	// Dismiss sourceMap when output should be optimized
+	const sourceMap = opts.optimize !== true
+
+	const result = await less.render(str, {
+		paths: [folderPath],
+		sourceMap: {
+			sourceMapFileInline: sourceMap,
+		}
+	})
+
+	return result.css
+
+}
\ No newline at end of file
diff --git a/src/postcss.js b/src/postcss.js
new file mode 100644
index 0000000..d2cc54a
--- /dev/null
+++ b/src/postcss.js
@@ -0,0 +1,35 @@
+'use strict'
+
+const postcss = require('postcss')
+const autoprefixer = require('autoprefixer')
+const cssnano = require('cssnano')
+
+/**
+ * Add vendor prefixes and minify CSS.
+ * @public
+ * @param {String} filePath - Absolute path to file.
+ * @param {String} str - CSS.
+ * @param {Object} opts - Optional options for the task.
+ * @returns {Promise<String>} Vendor prefixed and minified CSS.
+ */
+module.exports = async function(filePath, str, opts) {
+
+	// Dismiss sourceMap when output should be optimized
+	const sourceMap = opts.optimize !== true
+
+	const result = await postcss([
+
+		autoprefixer({ remove: false }),
+		cssnano({ safe: true })
+
+	]).process(str, {
+
+		from: filePath,
+		to: filePath,
+		map: sourceMap
+
+	})
+
+	return result.css
+
+}
\ No newline at end of file
diff --git a/test/index.js b/test/index.js
new file mode 100644
index 0000000..b232f85
--- /dev/null
+++ b/test/index.js
@@ -0,0 +1,162 @@
+'use strict'
+
+const os = require('os')
+const assert = require('chai').assert
+const uuid = require('uuid/v4')
+const index = require('./../src/index')
+
+const fsify = require('fsify')({
+	cwd: os.tmpdir()
+})
+
+describe('index()', function() {
+
+	it('should return an error when called without a filePath', async function() {
+
+		return index().then(() => {
+
+			throw new Error('Returned without error')
+
+		}, (err) => {
+
+			assert.strictEqual(err.message, `'filePath' must be a string`)
+
+		})
+
+	})
+
+	it('should return an error when called with invalid options', async function() {
+
+		const structure = await fsify([
+			{
+				type: fsify.FILE,
+				name: `${ uuid() }.less`
+			}
+		])
+
+		return index(structure[0].name, '').then(() => {
+
+			throw new Error('Returned without error')
+
+		}, (err) => {
+
+			assert.strictEqual(err.message, `'opts' must be undefined or an object`)
+
+		})
+
+	})
+
+	it('should return an error when called with a fictive filePath', async function() {
+
+		return index(`${ uuid() }.less`).then(() => {
+
+			throw new Error('Returned without error')
+
+		}, (err) => {
+
+			assert.isNotNull(err)
+			assert.isDefined(err)
+
+		})
+
+	})
+
+	it('should load LESS and transform it to CSS', async function() {
+
+		const structure = await fsify([
+			{
+				type: fsify.FILE,
+				name: `${ uuid() }.less`,
+				contents: ''
+			}
+		])
+
+		const result = await index(structure[0].name)
+
+		assert.include(result, 'sourceMappingURL')
+
+	})
+
+	it('should load LESS and transform it to optimized CSS when optimization enabled', async function() {
+
+		const structure = await fsify([
+			{
+				type: fsify.FILE,
+				name: `${ uuid() }.less`,
+				contents: ''
+			}
+		])
+
+		const result = await index(structure[0].name, { optimize: true })
+
+		assert.strictEqual(result, '')
+
+	})
+
+	describe('.in()', function() {
+
+		it('should be a function', function() {
+
+			assert.isFunction(index.in)
+
+		})
+
+		it('should return a default extension', function() {
+
+			assert.strictEqual(index.in(), '.less')
+
+		})
+
+		it('should return a default extension when called with invalid options', function() {
+
+			assert.strictEqual(index.in(''), '.less')
+
+		})
+
+		it('should return a custom extension when called with options', function() {
+
+			assert.strictEqual(index.in({ in: '.css' }), '.css')
+
+		})
+
+	})
+
+	describe('.out()', function() {
+
+		it('should be a function', function() {
+
+			assert.isFunction(index.in)
+
+		})
+
+		it('should return a default extension', function() {
+
+			assert.strictEqual(index.out(), '.css')
+
+		})
+
+		it('should return a default extension when called with invalid options', function() {
+
+			assert.strictEqual(index.out(''), '.css')
+
+		})
+
+		it('should return a custom extension when called with options', function() {
+
+			assert.strictEqual(index.out({ out: '.less' }), '.less')
+
+		})
+
+	})
+
+	describe('.cache', function() {
+
+		it('should be an array', function() {
+
+			assert.isArray(index.cache)
+
+		})
+
+	})
+
+})
\ No newline at end of file
diff --git a/test/less.js b/test/less.js
new file mode 100644
index 0000000..bfcd1ad
--- /dev/null
+++ b/test/less.js
@@ -0,0 +1,54 @@
+'use strict'
+
+const assert = require('chai').assert
+const less = require('./../src/less')
+
+describe('less()', function() {
+
+	it('should return an empty string when called with an empty LESS string', async function() {
+
+		const input = ''
+		const result = await less('.', input, { optimize: false })
+
+		assert.strictEqual(result, input)
+
+	})
+
+	it('should return an error when called with incorrect LESS', async function() {
+
+		const input = 'test'
+
+		return less('.', input, { optimize: false }).then(() => {
+
+			throw new Error('Returned without error')
+
+		}, (err) => {
+
+			assert.isNotNull(err)
+			assert.isDefined(err)
+
+		})
+
+	})
+
+	it('should return CSS with a source map when called with valid LESS', async function() {
+
+		const input = '.test { color: black; }'
+		const result = await less('.', input, { optimize: false })
+
+		assert.isString(result)
+		assert.include(result, 'sourceMappingURL')
+
+	})
+
+	it('should return CSS without a source map when called with valid LESS and optimization enabled', async function() {
+
+		const input = '.test { color: black; }'
+		const result = await less('.', input, { optimize: true })
+
+		assert.isString(result)
+		assert.notInclude(result, 'sourceMappingURL')
+
+	})
+
+})
\ No newline at end of file
diff --git a/test/postcss.js b/test/postcss.js
new file mode 100644
index 0000000..4a4291d
--- /dev/null
+++ b/test/postcss.js
@@ -0,0 +1,71 @@
+'use strict'
+
+const os = require('os')
+const assert = require('chai').assert
+const uuid = require('uuid/v4')
+const postcss = require('./../src/postcss')
+
+const fsify = require('fsify')({
+	cwd: os.tmpdir()
+})
+
+describe('postcss()', function() {
+
+	it('should return an error when called with incorrect CSS', async function() {
+
+		const structure = await fsify([
+			{
+				type: fsify.FILE,
+				name: `${ uuid() }.css`,
+				contents: 'test'
+			}
+		])
+
+		return postcss(structure[0].name, structure[0].contents, { optimize: false }).then(() => {
+
+			throw new Error('Returned without error')
+
+		}, (err) => {
+
+			assert.isNotNull(err)
+			assert.isDefined(err)
+
+		})
+
+	})
+
+	it('should return CSS with a source map when called with valid CSS', async function() {
+
+		const structure = await fsify([
+			{
+				type: fsify.FILE,
+				name: `${ uuid() }.css`,
+				contents: '.test { color: black; }'
+			}
+		])
+
+		const result = await postcss(structure[0].name, structure[0].contents, { optimize: false })
+
+		assert.isString(result)
+		assert.include(result, 'sourceMappingURL')
+
+	})
+
+	it('should return CSS without a source map when called with valid LESS and optimization enabled', async function() {
+
+		const structure = await fsify([
+			{
+				type: fsify.FILE,
+				name: `${ uuid() }.css`,
+				contents: '.test { color: black; }'
+			}
+		])
+
+		const result = await postcss(structure[0].name, structure[0].contents, { optimize: true })
+
+		assert.isString(result)
+		assert.notInclude(result, 'sourceMappingURL')
+
+	})
+
+})
\ No newline at end of file