HTML Minifier

1. What This Tool Actually Does

This HTML minifier runs a fixed sequence of text transformations on whatever markup you paste into the input box. First, it strips every HTML comment (<!-- ... -->) except ones that start with <!--[if — those are legacy Internet Explorer conditional comments and are deliberately left untouched. Next, it collapses any run of whitespace sitting directly between two tags (>\s+<) down to nothing, so a closing tag followed by a newline and indentation and an opening tag becomes one contiguous string. It then trims leading and trailing spaces/tabs on every line, collapses stacks of blank lines into a single newline, removes every remaining newline character entirely, and finally collapses any run of multiple spaces left in the text down to one.

The end result is a single unbroken line of HTML with no comments and no structural whitespace, while the actual visible text content of your page — headings, paragraphs, link labels — is left intact.

2. How to Use the HTML Minifier

1. Paste your HTML markup into the Input HTML panel on the left, or click Load Sample HTML to try it with a working WordPress template snippet.
2. The Minified Output panel updates instantly as you type — there is no submit button or server round-trip.
3. Check the green stats pill above the editors: it shows the exact input size, output size, and the percentage of bytes saved for your specific markup.
4. Click Copy to copy the minified result to your clipboard, then paste it wherever you need it — a build script, a static HTML export, or a CMS raw-HTML block.
5. Use Clear to reset both panels and start over.

3. Why Removing Whitespace and Comments Is Safe

Browsers render HTML according to the whitespace rules defined by the CSS specification. Outside of a handful of whitespace-sensitive elements, a run of spaces, tabs, and newlines sitting between two block-level tags has no visual effect — it either collapses to nothing at render time or was only ever there to make the source readable for a developer. Removing it changes the bytes the browser downloads but not the pixels it paints. HTML comments are even simpler: the browser's HTML parser discards them the moment it builds the DOM, so a comment is pure dead weight from the network's perspective.

The one historical exception is the IE conditional comment, written as <!--[if lt IE 9]>...<![endif]-->. Older versions of Internet Explorer treated this specific comment syntax as a real conditional directive, so deleting it could silently remove IE-only stylesheet links or polyfill scripts. The tool's regex uses a negative lookahead, (?!\[if), specifically so these blocks survive minification untouched.

4. A Real Example

Take this small promo block as input:

<div class="promo">
  <!-- badge -->
  <h2>Save 20%</h2>
</div>

Running it through the minifier produces:

<div class="promo"><h2>Save 20%</h2></div>

The comment is gone entirely, and every newline plus every run of indentation between tags collapsed to nothing — but the class name, tag structure, and the text "Save 20%" are byte-for-byte identical to the source. Paste your own markup into the tool above and the live stats pill will show the exact input bytes, output bytes, and percentage saved for that specific file.

5. Practical Use Cases

• WordPress custom HTML blocks: Compact markup before pasting it into a Gutenberg Custom HTML block or a theme's header.php snippet, where every stored byte adds up across thousands of page loads.
• Static landing page exports: Agencies exporting a one-off campaign landing page can strip development comments and indentation before uploading the final HTML file to a host.
• Embedding HTML fragments in JS: Pasting an HTML string into a JavaScript template literal, JSON config value, or a CMS "raw HTML" widget, where compact single-line markup is easier to store and diff.
• Pre-Gzip byte reduction: Running HTML through this tool before the server applies Gzip/Brotli compression (see the Compression Tester) shrinks the uncompressed payload the compressor has to work with.

6. Common Mistakes & Limitations

• Whitespace-sensitive elements: This is a regex-based text minifier, not a DOM-aware parser — it does not special-case <pre>, <textarea>, or inline <script> content. Formatting inside those tags can be altered. Always review output before shipping markup that relies on preserved whitespace.
• Not a substitute for server compression: Minification removes source bytes once; it does not replace Gzip or Brotli, which re-encode every response on the fly. Use both together for maximum savings.
• Server-side template delimiters: The regexes only target HTML comments and inter-tag whitespace, so PHP/Twig/Blade syntax is left alone — but if your templating engine relies on exact whitespace between tags for output formatting (uncommon), verify the rendered result in staging.
• One-line output is hard to diff: Because everything collapses onto a single line, minified HTML is not meant for version control — keep your readable source as the file you edit, and minify only the deployment copy.