HTML Beautifier — Format HTML Online Free
Paste messy, minified, or inherited HTML and get back clean, properly indented code instantly. This free HTML beautifier online uses the js-beautify library to format markup with consistent indentation, and also checks for missing alt attributes and deprecated tags — two common accessibility and SEO issues developers miss. To format the CSS stylesheets or JSON data in your project, those tools are available too.
How to Use the HTML Beautifier
- Paste your raw, minified, or messy HTML into the left input panel.
- Choose an indent size — 2 spaces, 4 spaces, or tabs — and toggle Wrap attributes if you want each HTML attribute on its own line.
- Click Beautify HTML or enable Format on Paste for instant formatting.
- Review the yellow and red warning badges for missing
altattributes and deprecated HTML tags. - Copy the formatted output to your clipboard or download it as a
.htmlfile.
Key Features
- Powered by the industry-standard js-beautify library for reliable HTML formatting.
- Choice of 2-space, 4-space, or tab indentation to match your project's style guide.
- Attribute wrapping mode: places each HTML attribute on its own line for easier diffing.
- Accessibility linter: counts
<img>tags missing thealtattribute. - Deprecated tag detector: flags
<center>,<font>,<marquee>, and more. - Minify mode: strips comments and collapses whitespace for production-ready HTML.
- Download the beautified result as a
.htmlfile. - Format-on-paste for automatic formatting as you work.
Use Cases
Format messy HTML code pasted from a CMS or builder
Page builders and CMS platforms often export HTML that is heavily nested and minimally indented. Pasting that output into this HTML formatter gives you a readable, maintainable structure you can work with in your code editor.
Indent HTML for code review and pull requests
Reviewers struggle to read unindented HTML. Running your template through the beautifier before opening a pull request makes structural changes immediately visible, reducing review time and the chance of missed bugs.
Check for missing alt attributes for accessibility and SEO
The alt attribute linter scans every <img> tag and flags those missing alt="". This directly supports WCAG 2.1 compliance and improves how search engines index your images — two wins from one check.
Detect and replace deprecated HTML5 tags
Tags like <center>, <font>, and <marquee> were removed in HTML5. The beautifier's linter identifies every deprecated tag in your markup so you can replace them with modern CSS equivalents before the code ships.
Pretty print HTML from scraped or generated sources
Web scraping tools and HTML-generating libraries often produce single-line output. The HTML pretty printer instantly restructures that output into human-readable markup, making it easy to inspect and extract the data you need. For scraping projects that deliver output as CSV or XML, those formatters can help you clean the data further.
FAQ's
No. HTML is whitespace-insensitive for block elements. Adding indentation and line breaks does not change how browsers render the page. Inline elements like <span> and <a> inside running text can be marginally affected by extra whitespace, which is why the beautifier is careful about inline element handling.
The alt attribute provides a text alternative for screen readers used by visually impaired users, satisfying WCAG 2.1 accessibility guidelines. It is also displayed when the image fails to load, and it is indexed by search engines as part of image SEO. Missing alt attributes reduce your site's accessibility score and can hurt search rankings.
Tags removed or deprecated in HTML5 include: <center> (use CSS text-align), <font> (use CSS font properties), <marquee> (use CSS animations), and <blink> (never standardized). The tool also flags <frame>, <frameset>, <strike>, <big>, <tt>, and <basefont>.
Yes. Select "Tab" in the indent size dropdown and the formatter will use tab characters instead of spaces. Tab-based indentation is preferred by some style guides (such as WordPress PHP) and lets each developer set their own visual indent width in their editor.
When enabled, js-beautify uses its force-expand-multiline mode, which places each HTML attribute on its own indented line. This is extremely useful for complex elements with many attributes — like <input> tags or custom web components — because it makes each attribute visible and easy to review in a diff.
No. All formatting happens entirely in your browser using the js-beautify library running client-side. Your code never leaves your device and is never transmitted to any external server.
Just open this page in any modern browser — no download, plugin, or account required. Paste your HTML, click Beautify HTML, and copy or download the formatted result. The entire tool runs client-side with no installation needed.
Clean, well-indented HTML is easier to review, debug, and maintain — and it is also less likely to contain hidden accessibility problems. This free HTML beautifier online goes beyond simple indentation by actively linting your markup for two of the most common issues in real-world HTML: missing alt attributes on images and the use of tags that HTML5 has deprecated. Both issues are invisible to the naked eye in a wall of minified markup but are immediately obvious in a properly formatted document. Whether you are cleaning up a third-party template, reviewing scraped content, or standardizing a team's HTML conventions, this tool handles it in seconds with no installation and no data ever leaving your browser.