HTML Beautifier

format and indent HTML code with configurable settings

By Bikram NathLast updated May 19, 2026

Paste minified or messy HTML and get back properly indented, nested markup in one click. Useful when a CMS export hands you a wall of tags with no whitespace — for example, a 4KB single-line Mailchimp template becomes scannable, attributed markup with configurable 2- or 4-space indentation. Unlike a general code editor's format-on-save, this runs entirely on the page with no install required.

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What is HTML Beautifier?

HTML Beautifier takes raw HTML — minified, concatenated, or just inconsistently indented — and re-serializes it with correct hierarchical indentation and normalized whitespace. Feed it something like `<html><head><title>T</title></head><body>Hi</body></html>` and you get back a properly nested, multi-line document you can actually read and diff.

Developers reach for this when Prettier is overkill for a one-off task, or when the HTML they're looking at isn't part of a local project — scraped markup, a third-party widget's minified output, or an email template dropped into a support ticket. Tools like VS Code's built-in formatter require a file on disk; browser devtools pretty-print the live DOM, which diverges from source if JavaScript has mutated it. This tool formats the literal text you paste.

One thing to know: the formatter works on text, not on a parsed DOM tree. That means it won't catch or correct invalid nesting — unclosed tags, block elements inside inline elements, or duplicate IDs — it just re-indents whatever structure is already there. If you need validation alongside formatting, run the output through the W3C Markup Validator afterward.

When to use HTML Beautifier

✓Restore readability to a minified HTML email template before editing inline styles or conditional merge tags.

→Normalize inconsistent indentation across files before opening a pull request so the diff shows only real changes.

⚡Extract and format an embedded HTML snippet from a JSON API response before debugging its structure.

Frequently Asked Questions

Will the beautifier change anything other than whitespace?

In normal operation, no — it only adjusts indentation and line breaks. Attribute order, attribute quoting style, tag casing, and content are left untouched. If you paste `<IMG SRC='x'>` you'll get back `<IMG SRC='x'>` with corrected indentation, not `<img src="x">`. Some formatters normalize these things, but this tool's scope is whitespace only. If you need attribute sorting or quote normalization, a full Prettier run with the HTML plugin is the right tool.

Why does the formatted output look wrong for inline elements like `` inside ``?

Inline elements — ``, `<a>`, ``, `` — are treated as block-level for indentation purposes by most text-based HTML formatters, including this one. That means you may see a `` on its own indented line even though it sits inline in the rendered page. This is a known trade-off of text-based formatting versus DOM-aware formatting. The output is still semantically correct HTML; it just won't match what Prettier's HTML plugin produces with its inline-element-aware line-wrapping logic.

How large an HTML file can I paste before the browser slows down?

In practice, files up to roughly 500KB format without noticeable lag in a modern browser. Above that, the string operations start to compete with the main thread. The V8 string length limit is around 512MB, so you won't hit a hard crash on realistic HTML, but the UI will become unresponsive on files in the multi-megabyte range. If you're routinely formatting files larger than 1MB, a local tool like Prettier via `npx prettier --parser html` is more appropriate.

Does it handle HTML mixed with templating syntax like Jinja, Handlebars, or Blade?

Template syntax inside HTML — `{{ variable }}`, `{% if %}`, `@foreach`, Blade directives — is treated as opaque text content. The formatter won't break it, but it also won't understand it. A Handlebars `{{#each items}}` block that spans multiple HTML tags will be indented based on the surrounding HTML structure, which may not align with what you'd want. For Jinja or Blade templates, using an editor extension that understands the specific templating language produces better results.

How is this different from using browser DevTools to copy the outer HTML?

DevTools' 'Copy outerHTML' gives you the current DOM state, which reflects all JavaScript mutations — dynamically injected nodes, framework-rendered components, attributes added at runtime. If you need the original server-sent HTML before any script runs, or the raw HTML from a file you're not hosting locally, DevTools won't help. This tool formats whatever text you paste directly, so it works on static files, email templates, CMS exports, or HTML snippets from an API response without needing to load the document in a browser.

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