HTMLMinifier

HTMLMinifier is a highly configurable, well-tested, JavaScript-based HTML minifier.

See corresponding blog post for all the gory details of how it works, description of each option, testing results and conclusions.

Test suite is available online.

Also see corresponding Ruby wrapper, and for Node.js, Grunt plugin, Gulp module, Koa middleware wrapper and Express middleware wrapper.

For lint-like capabilities take a look at HTMLLint.

Minification comparison

How does HTMLMinifier compare to other solutions — HTML Minifier from Will Peavy (1st result in Google search for "html minifier") as well as htmlcompressor.com and minimize?

Options Quick Reference

Most of the options are disabled by default.

Sorting attributes / style classes

Minifier options like sortAttributes and sortClassName won't impact the plain-text size of the output. However, they form long repetitive chains of characters that should improve compression ratio of gzip used in HTTP compression.

Special cases

Ignoring chunks of markup

If you have chunks of markup you would like preserved, you can wrap them <!-- htmlmin:ignore -->.

Preserving SVG tags

SVG tags are automatically recognized, and when they are minified, both case-sensitivity and closing-slashes are preserved, regardless of the minification settings used for the rest of the file.

Working with invalid markup

HTMLMinifier can't work with invalid or partial chunks of markup. This is because it parses markup into a tree structure, then modifies it (removing anything that was specified for removal, ignoring anything that was specified to be ignored, etc.), then it creates a markup out of that tree and returns it.

Input markup (e.g. <p id="">foo)

↓

Internal representation of markup in a form of tree (e.g. { tag: "p", attr: "id", children: ["foo"] })

↓

Transformation of internal representation (e.g. removal of id attribute)

↓

Output of resulting markup (e.g. <p>foo</p>)

HTMLMinifier can't know that original markup was only half of the tree; it does its best to try to parse it as a full tree and it loses information about tree being malformed or partial in the beginning. As a result, it can't create a partial/malformed tree at the time of the output.

Installation Instructions

From NPM for use as a command line app:

npm install html-minifier -g

From NPM for programmatic use:

npm install html-minifier

From Git:

git clone git://github.com/kangax/html-minifier.git
cd html-minifier
npm link .

Usage

Note that almost all options are disabled by default. For command line usage please see html-minifier --help for a list of available options. Experiment and find what works best for you and your project.

• Sample command line: html-minifier --collapse-whitespace --remove-comments --remove-optional-tags --remove-redundant-attributes --remove-script-type-attributes --remove-tag-whitespace --use-short-doctype --minify-css true --minify-js true

Node.js

var minify = require('html-minifier').minify;
var result = minify('<p title="blah" id="moo">foo</p>', {
  removeAttributeQuotes: true
});
result; // '<p title=blah id=moo>foo</p>'

Gulp

const { src, dest, series } = require('gulp');
const htmlMinify = require('html-minifier');

const options = {
  includeAutoGeneratedTags: true,
  removeAttributeQuotes: true,
  removeComments: true,
  removeRedundantAttributes: true,
  removeScriptTypeAttributes: true,
  removeStyleLinkTypeAttributes: true,
  sortClassName: true,
  useShortDoctype: true,
  collapseWhitespace: true
};

function html() {
  return src('app/**/*.html')
    .on('data', function(file) {
      const buferFile = Buffer.from(htmlMinify.minify(file.contents.toString(), options))
      return file.contents = buferFile
    })
    .pipe(dest('build'))
}

exports.html = series(html)

Running benchmarks

Benchmarks for minified HTML:

node benchmark.js