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HTML Formatter Online — Free HTML Beautifier, Minifier & Validator

HTML Formatter

Format, minify, and validate HTML with attribute sorting and template support.

Free online HTML formatter and beautifier. Paste your HTML, choose indentation style (2 or 4 spaces, tabs), configure attribute wrapping and sorting, and format instantly. Supports Handlebars, EJS, and Jinja template syntax. Minify HTML for production, validate structure with error detection, convert HTML to JSX for React projects, or clean up messy markup from CMS editors. Formats embedded CSS and JavaScript automatically. Runs entirely in your browser — no data is ever sent to a server.

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Tags: html, format, beautify, minify, validate, prettify, jsx

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How to HTML Formatter Online

  1. Paste your HTML into the input area on the left, or upload an .html file using the upload button. You can also drag and drop a file directly onto the input area.

  2. Choose your indentation style — 2 spaces, 4 spaces, or tabs — and configure attribute wrapping mode (auto, force, expand, aligned, or preserve).

  3. Optionally enable Sort Attributes to alphabetically order all HTML attributes on each element for consistent, diff-friendly output.

  4. Click the Format button or press ⌘↵ (Mac) / Ctrl+Enter (Windows) to beautify your HTML instantly with syntax highlighting.

  5. Use Minify to collapse the HTML to a single line for production embedding, Validate to check for structural errors, → JSX to convert to React-compatible syntax, or Cleanup to remove deprecated tags and inline styles.

  6. Copy the formatted output with ⌘⇧C, download it as an .html file, or use the Share button to generate a gzip-compressed shareable URL.

HTML Formatter Features

  • HTML formatter with configurable indentation: 2 spaces, 4 spaces, or tabs to match your team's coding standards.

  • 5 attribute wrapping modes: auto (wrap when line exceeds threshold), force (one attribute per line), force-expand (always one per line), force-aligned (aligned to first attribute), and preserve (keep original formatting).

  • Sort Attributes: alphabetically orders all HTML attributes for consistent, diff-friendly, and code-review-friendly output.

  • HTML minifier: collapses formatted HTML to a single line by removing whitespace, comments, and unnecessary characters for production use.

  • HTML validator with structural checks: unclosed tags, mismatched nesting, duplicate IDs, missing alt attributes, deprecated tags, and invalid element nesting.

  • HTML to JSX converter: transforms class to className, for to htmlFor, style strings to style objects, boolean attributes, and comments to JSX comments — ready for React projects.

  • HTML cleanup: removes inline styles, empty elements, deprecated tags, and editor cruft from CMS-generated HTML.

  • Embedded CSS and JavaScript formatting: automatically formats inline <style> and <script> blocks within your HTML.

  • Template syntax support: handles Handlebars {{ }}, EJS <% %>, and Jinja {% %} template literals without breaking formatting.

  • Syntax highlighting with color-coded tags, attributes, values, comments, entities, and template expressions.

  • Document type detection: automatically identifies full HTML documents, fragments, and template files.

  • HTML statistics: element count, nesting depth, and output byte size displayed as meta badges.

  • Shareable URLs: gzip-compresses your HTML into a URL parameter so you can share documents with teammates.

  • Works entirely in your browser — no HTML is ever sent to any server. Your markup stays completely private.

  • Keyboard shortcuts for power users: ⌘⇧F to format, ⌘⇧M to minify, ⌘⇧V to validate, ⌘⇧K to clear.

  • Large-input warning with byte count — alerts you when the input may slow down formatting.

  • Auto-format on type: toggle live formatting as you type with the Auto Format checkbox.

Frequently Asked Questions

Is this HTML formatter free?
Yes, DevFlow HTML Formatter is completely free with no usage limits. All formatting, minification, validation, JSX conversion, and cleanup runs directly in your browser — no account or signup required.
Is my HTML data safe?
Your HTML is processed entirely in your browser using the js-beautify JavaScript library. No HTML is ever transmitted to a server or stored anywhere outside your browser. Your markup stays completely private on your machine.
What does HTML formatting do?
HTML formatting (also called beautifying or prettifying) takes compact, minified, or poorly indented HTML and reformats it with consistent indentation, line breaks, and attribute alignment. This makes the markup human-readable and easier to debug, review, and maintain.
What is HTML minification?
HTML minification removes unnecessary whitespace, line breaks, comments, and optional closing tags from HTML to reduce file size. Minified HTML loads faster in browsers and is commonly used for production deployment, embedding HTML in JavaScript strings, or storing HTML in API responses and databases.
What does attribute sorting do?
Attribute sorting alphabetically orders all HTML attributes on each element. For example, <div style='...' class='...' id='...'> becomes <div class='...' id='...' style='...'>. This produces consistent, predictable output that is easier to scan in code reviews and creates smaller diffs when attributes change.
What attribute wrapping modes are available?
Five modes are supported: Auto wraps attributes only when a line exceeds the configured width. Force puts each attribute on its own line. Force-expand always uses one attribute per line even on short elements. Force-aligned aligns attributes vertically with the first attribute. Preserve keeps the original formatting from the input HTML.
Does it support template syntax like Handlebars or EJS?
Yes. The formatter recognizes and preserves Handlebars {{ }}, EJS <% %>, and Jinja {% %} template expressions within your HTML. Template expressions are treated as opaque tokens — the formatter indents the surrounding HTML without modifying the template syntax.
How does HTML to JSX conversion work?
The JSX converter transforms standard HTML into valid React JSX syntax. It converts class to className, for to htmlFor, inline style strings to JavaScript objects, event handlers to camelCase, boolean attributes to explicit JSX expressions, HTML comments to JSX comments, and ensures all void elements are self-closing. The output can be pasted directly into a React component.
What HTML validation checks are performed?
The validator checks for: unclosed or mismatched tags with line/column positions, duplicate id attributes, missing required attributes (alt on images, href on links), deprecated HTML tags (font, center, marquee, etc.), and unclosed void elements. Each issue includes its severity (error or warning) and exact location.
Does it format embedded CSS and JavaScript?
Yes. The formatter automatically detects inline <style> and <script> blocks and formats their content using appropriate rules. CSS inside style tags gets proper indentation, and JavaScript inside script tags gets formatted while preserving operator semantics.
What does HTML cleanup do?
The cleanup feature removes common markup cruft: inline style attributes, empty elements with no content or purpose, deprecated HTML tags (font, center, blink, marquee), and optionally data-* attributes and HTML comments. This is especially useful for cleaning up HTML exported from CMS editors, email builders, or WYSIWYG tools.
Can I upload an HTML file?
Yes. Click the upload icon in the input panel header to select an .html or .htm file from your computer. You can also drag and drop files directly onto the input area. The file contents are loaded for formatting.
Does it work offline?
Yes. All formatting logic is bundled with the page as pure JavaScript (js-beautify). Once the page has loaded, the HTML Formatter works without an internet connection — no network requests are made during formatting.

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