HTML Formatter

HTML collapses runs of whitespace to a single space when rendering, which is why you can indent markup freely. There are exceptions, and a formatter that ignores them will change how your page looks.

<pre> and <textarea> preserve whitespace exactly. Re-indenting their contents changes what the user sees. Both are passed through untouched here.

<script> and <style> contain code, not markup. Their contents are copied verbatim rather than parsed as HTML.

Inline elements are whitespace-sensitive at their boundaries. This:

<p>Read the <a href="/docs">docs</a> first.</p>

renders differently if a newline is inserted before </a>, because that whitespace becomes a rendered space. This is why aggressive minifiers can push punctuation onto the wrong side of a link.

Minification removes comments and collapses whitespace between tags. That is all — deliberately.

What it will not do:

• Remove optional closing tags such as </li> and </p>. Legal HTML, but it makes the source much harder to reason about and breaks some downstream parsers.
• Strip quotes from attribute values. Legal for simple values, a silent bug for anything containing a space.
• Reorder or deduplicate attributes.
• Inline or minify CSS and JavaScript inside the document. Use the CSS & JS minifier for those.

For a production build you want a full pipeline that also inlines critical CSS and defers scripts. This is for the case where you have a snippet, an email template, or a page you want to shrink quickly without setting any of that up.