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Utiloom

HTML Formatter

Format bounded HTML and embedded JavaScript or CSS with explicit whitespace and layout policies, stable verification, and local export.

LocalNo retention

Reviewed July 13, 2026

Guide, examples, and validation Show

About this tool

Beautify raw HTML so you can read, review, and debug markup more easily in the browser.

HTML Formatter is most useful when copied markup is technically readable by browsers but hard for humans to scan. It gives developers a quick way to re-indent pasted templates, snippets, embeds, and generated fragments before debugging or sharing them in docs, tickets, or pull requests.

  • Uses Prettier 3.8.1 HTML, Babel, Estree, and PostCSS plugins to format markup plus optional embedded script and style content.
  • Controls tabs or spaces, print width, HTML whitespace sensitivity, one-attribute-per-line layout, closing bracket placement, and embedded language formatting.
  • Runs locally with input and output bounds and requires the result to remain stable when formatted again with the same policy.

How to use HTML Formatter

Paste the HTML snippet you want to clean up, run the formatter, and inspect the nested output before copying it back into your editor. If the markup still looks suspicious after formatting, use the result as a readable starting point for validation rather than assuming the formatter has fixed semantic HTML issues.

When this tool is useful

  • Uses Prettier 3.8.1 HTML, Babel, Estree, and PostCSS plugins to format markup plus optional embedded script and style content.
  • Controls tabs or spaces, print width, HTML whitespace sensitivity, one-attribute-per-line layout, closing bracket placement, and embedded language formatting.
  • Runs locally with input and output bounds and requires the result to remain stable when formatted again with the same policy.

Examples you can test

Load an example, compare the result with the expected output, then replace it with your own input.

Format a compressed snippet

Example input

<div><h1>Title</h1><p>Copy</p></div>

Expected output

Indented HTML with nested tags on separate lines

Readable markup is easier to review before pasting into docs, templates, or issue comments.

Inspect copied embed code

Example input

<iframe src="..."></iframe><script>...</script>

Expected output

Formatted embed structure

Formatting helps review structure, but it does not make third-party embeds safe by itself.

Validation checklist

  • Validate important markup after formatting if semantic correctness matters.
  • Review scripts and iframes from unknown sources before using them.
  • Keep the original snippet when debugging a formatting or escaping issue.

Frequently asked questions

Does this validate HTML too?

No. This tool formats markup and surfaces parser errors, but it is not a full HTML validator.

Can I use this on long HTML snippets?

Input is limited to 500,000 characters and generated output to 2,000,000 characters. Formatting runs locally in the browser.

Does the formatter fix broken or invalid HTML tags?

Prettier reports markup it cannot parse and may normalize syntax according to its HTML parser. It is not standards validation and does not prove that markup is accessible, safe, or rendered as intended.

How does the tool handle inline elements versus block elements for indentation?

Block-level elements like div, section, and article get their own indentation level, while inline elements like span and strong remain on the same line as their parent content.

Can I choose the indentation style, such as tabs versus spaces?

Yes, you can select between tabs and spaces and set the number of spaces per indent level, typically 2 or 4, to match your project's code style.

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