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    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 and minimize?

    Site Original size (KB) HTMLMinifier minimize Will Peavy
    Google 48 44 48 49 48
    HTMLMinifier 154 117 128 133 128
    Twitter 203 162 195 219 195
    Stack Overflow 254 196 208 216 205
    Bootstrap CSS 271 260 269 229 269
    BBC 288 230 280 281 272
    Amazon 508 439 495 501 n/a
    Wikipedia 533 434 517 536 517
    New York Times 699 619 693 683 n/a
    NBC 700 657 698 699 n/a
    Eloquent Javascript 870 815 840 864 n/a
    ES6 table 5308 4529 5025 n/a n/a
    ES draft 6082 5456 5624 n/a n/a

    Options Quick Reference

    Most of the options are disabled by default.

    Option Description Default
    caseSensitive Treat attributes in case sensitive manner (useful for custom HTML tags) false
    collapseBooleanAttributes Omit attribute values from boolean attributes false
    collapseInlineTagWhitespace Don't leave any spaces between display:inline; elements when collapsing. Must be used in conjunction with collapseWhitespace=true false
    collapseWhitespace Collapse white space that contributes to text nodes in a document tree false
    conservativeCollapse Always collapse to 1 space (never remove it entirely). Must be used in conjunction with collapseWhitespace=true false
    customAttrAssign Arrays of regex'es that allow to support custom attribute assign expressions (e.g. '<div flex?="{{mode != cover}}"></div>') [ ]
    customAttrCollapse Regex that specifies custom attribute to strip newlines from (e.g. /ng-class/)
    customAttrSurround Arrays of regex'es that allow to support custom attribute surround expressions (e.g. <input {{#if value}}checked="checked"{{/if}}>) [ ]
    customEventAttributes Arrays of regex'es that allow to support custom event attributes for minifyJS (e.g. ng-click) [ /^on[a-z]{3,}$/ ]
    decodeEntities Use direct Unicode characters whenever possible false
    html5 Parse input according to HTML5 specifications true
    ignoreCustomComments Array of regex'es that allow to ignore certain comments, when matched [ /^!/ ]
    ignoreCustomFragments Array of regex'es that allow to ignore certain fragments, when matched (e.g. <?php ... ?>, {{ ... }}, etc.) [ /<%[\s\S]*?%>/, /<\?[\s\S]*?\?>/ ]
    includeAutoGeneratedTags Insert tags generated by HTML parser true
    keepClosingSlash Keep the trailing slash on singleton elements false
    maxLineLength Specify a maximum line length. Compressed output will be split by newlines at valid HTML split-points
    minifyCSS Minify CSS in style elements and style attributes (uses clean-css) false (could be true, Object, Function(text, type))
    minifyJS Minify JavaScript in script elements and event attributes (uses UglifyJS) false (could be true, Object, Function(text, inline))
    minifyURLs Minify URLs in various attributes (uses relateurl) false (could be String, Object, Function(text))
    preserveLineBreaks Always collapse to 1 line break (never remove it entirely) when whitespace between tags include a line break. Must be used in conjunction with collapseWhitespace=true false
    preventAttributesEscaping Prevents the escaping of the values of attributes false
    processConditionalComments Process contents of conditional comments through minifier false
    processScripts Array of strings corresponding to types of script elements to process through minifier (e.g. text/ng-template, text/x-handlebars-template, etc.) [ ]
    quoteCharacter Type of quote to use for attribute values (' or ")
    removeAttributeQuotes Remove quotes around attributes when possible false
    removeComments Strip HTML comments false
    removeEmptyAttributes Remove all attributes with whitespace-only values false (could be true, Function(attrName, tag))
    removeEmptyElements Remove all elements with empty contents false
    removeOptionalTags Remove optional tags false
    removeRedundantAttributes Remove attributes when value matches default. false
    removeScriptTypeAttributes Remove type="text/javascript" from script tags. Other type attribute values are left intact false
    removeStyleLinkTypeAttributes Remove type="text/css" from style and link tags. Other type attribute values are left intact false
    removeTagWhitespace Remove space between attributes whenever possible. Note that this will result in invalid HTML! false
    sortAttributes Sort attributes by frequency false
    sortClassName Sort style classes by frequency false
    trimCustomFragments Trim white space around ignoreCustomFragments. false
    useShortDoctype Replaces the doctype with the short (HTML5) doctype false

    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://
    cd html-minifier
    npm link .


    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


    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>'

    Running benchmarks

    Benchmarks for minified HTML:

    node benchmark.js


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