HTML minifier with lint-like capabilities.

HTMLMinifier is a highly configurable, well-tested, Javascript-based HTML minifier, with lint-like capabilities.

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, and Koa middleware wrapper.

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?

SiteOriginal size (KB)HTMLMinifierminimizeWill
HTMLMinifier page48.837.341.843.341.9
ES6 table117.979.994.19291.9
Eloquent Javascript869.5830838872n/a
removeCommentsStrip HTML commentsfalse
removeCommentsFromCDATAStrip HTML comments from scripts and stylesfalse
removeCDATASectionsFromCDATARemove CDATA sections from script and style elementsfalse
collapseWhitespaceCollapse white space that contributes to text nodes in a document tree.false
conservativeCollapseAlways collapse to 1 space (never remove it entirely). Must be used in conjunction with collapseWhitespace=truefalse
preserveLineBreaksAlways collapse to 1 line break (never remove it entirely) when whitespace between tags include a line break. Must be used in conjunction with collapseWhitespace=truefalse
collapseBooleanAttributesOmit attribute values from boolean attributesfalse
removeAttributeQuotesRemove quotes around attributes when possible.false
removeRedundantAttributesRemove attributes when value matches default.false
preventAttributesEscapingPrevents the escaping of the values of attributes.false
useShortDoctypeReplaces the doctype with the short (HTML5) doctypefalse
removeEmptyAttributesRemove all attributes with whitespace-only valuesfalse
removeScriptTypeAttributesRemove type="text/javascript" from script tags. Other type attribute values are left intact.false
removeStyleLinkTypeAttributesRemove type="text/css" from style and link tags. Other type attribute values are left intact.false
removeOptionalTagsRemove unrequired tagsfalse
removeIgnoredRemove all tags starting and ending with <%, %>, <?, ?>false
removeEmptyElementsRemove all elements with empty contentsfalse
lintToggle lintingfalse
keepClosingSlashKeep the trailing slash on singleton elementsfalse
caseSensitiveTreat attributes in case sensitive manner (useful for custom HTML tags.)false
minifyJSMinify Javascript in script elements and on* attributes (uses UglifyJS)false (could be true, false, Object (options))
minifyCSSMinify CSS in style elements and style attributes (uses clean-css)false (could be true, false, Object (options))
minifyURLsMinify URLs in various attributes (uses relateurl)false (could be Object (options))
ignoreCustomCommentsArray of regex'es that allow to ignore certain comments, when matched[ ]
processScriptsArray of strings corresponding to types of script elements to process through minifier (e.g. text/ng-template, text/x-handlebars-template, etc.)[ ]
maxLineLengthSpecify a maximum line length. Compressed output will be split by newlines at valid HTML split-points.
customAttrAssignArrays of regex'es that allow to support custom attribute assign expressions (e.g. '<div flex?="{{mode != cover}}"></div>')[ ]
customAttrSurroundArrays of regex'es that allow to support custom attribute surround expressions (e.g. <input {{#if value}}checked="checked"{{/if}}>)[ ]
customAttrCollapseRegex that specifies custom attribute to strip newlines from (e.g. /ng\-class/)
quoteCharacterType of quote to use for attribute values (' or ")"

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

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.

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 ingored, 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.

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 .

For command line usage please see html-minifier --help

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>' 

Benchmarks for minified HTML:

node benchmark.js