HTML formatter online, prettify and indent HTML free

Have a wall of minified HTML that's impossible to read? Use ToolHQ's free HTML formatter to instantly prettify and indent any HTML code right in your browser.

ToolHQ's HTML formatter is a free browser-based tool that formats minified or unindented HTML into clean, properly indented markup, with your code never sent to any server.

Minified HTML is great for production websites but completely unreadable for debugging, reviewing, or learning. One click of the format button turns a single-line jumble into structured, readable code.

Key Takeaways

• Formats minified HTML into properly indented, human-readable markup instantly
• Handles nested elements, attributes, and standard HTML5 structure correctly
• Your code never leaves your browser -- formatting runs entirely client-side
• Free with no login, no rate limits, and no file size restrictions displayed
• Works for HTML snippets as well as full page source code

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What is HTML formatting and why does it matter?

HTML formatting (also called prettifying or beautifying) is the process of adding consistent indentation, line breaks, and whitespace to HTML markup to make it readable to humans. Browsers don't care about whitespace in HTML -- they parse the structure, not the spacing. But developers do care.

According to the W3C HTML specification, HTML is a markup language where nesting relationships between elements define the document structure. Proper indentation reflects that nesting visually -- a child element is indented one level deeper than its parent. Without consistent formatting, the nested structure becomes invisible in the source code.

The MDN HTML documentation describes HTML as the backbone of the web, used to define the structure and meaning of web content. When you inspect the source code of websites with developer tools, the HTML you see is often formatted -- the actual served HTML may be minified to reduce page load size.

Situations where HTML formatting is essential:

• Reading the source HTML of a page you didn't write (inspecting competitor sites, debugging CMS output)
• Reviewing minified HTML templates in build output
• Understanding the structure of a complex HTML email template
• Learning HTML by studying well-formatted examples
• Debugging layouts by seeing nested structure clearly

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When you need to format HTML

The HTML formatter is most useful when you're handed HTML that someone or something else generated without human readability in mind.

Mini-story: Aryan is a 31-year-old web developer who was tasked with auditing the accessibility of a client's legacy website. He viewed source on the client's homepage and got 8,000 characters of unformatted HTML on a single line -- the output of an older CMS that minified everything. He copied it into ToolHQ's HTML formatter and clicked Format. Within two seconds, the same 8,000 characters were spread across 180 properly indented lines, making the nesting structure and ARIA attributes immediately visible. He identified three missing aria-label attributes in under three minutes.

Common situations where HTML formatting is the right tool:

• Copying HTML from a website's view-source or browser dev tools
• Receiving HTML email templates from a designer that have no indentation
• Debugging output from an HTML-generating library or template engine
• Reading HTML from a web scraper output file
• Reformatting an HTML file that got mangled during a code editor migration

Format your HTML at ToolHQ

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How to format HTML

1. Open ToolHQ's HTML formatter in your browser.
2. Paste your HTML into the input area. This can be a full page's HTML or just a snippet.
3. Click Format (or the tool may format in real time as you paste).
4. Copy the formatted output from the result area, or download it as an.html file.

The formatter preserves all attribute values, text content, and structural relationships -- it only changes whitespace and indentation, not the meaning of the HTML.

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HTML formatting best practices

Consistent indentation: The standard in most codebases is 2 or 4 spaces per nesting level. The formatter applies consistent indentation throughout, making the nesting depth of any element immediately visible.

Attributes on one line vs. multiple lines: Most formatters keep attributes on the same line as the opening tag unless the tag becomes very long. Some formatters offer "one attribute per line" mode for long tags with many attributes -- useful when reviewing form elements or SVG tags with extensive attribute lists.

Inline vs. block elements: Inline elements like <span>, <a>, and <strong> don't necessarily get their own line -- they may remain inline with surrounding text. Block elements like <div>, <p>, <section>, and <header> typically get their own lines. Good HTML formatters respect this distinction.

Mini-story: Yuki, a 24-year-old junior developer, was learning CSS layout by inspecting how a popular portfolio website was structured. She copied the hero section HTML from the page source -- about 300 characters of unindented markup. Pasting it into the HTML formatter revealed it was a 5-level deep nesting of div elements: main > section > div > div > div. Seeing the structure clearly helped her understand why the parent had display: flex and why the spacing wasn't working the way she expected.

For minifying HTML for production (the reverse of formatting), use ToolHQ's CSS minifier for the stylesheet and JS minifier for scripts. For converting Markdown to HTML, try ToolHQ's Markdown to HTML converter. Browse all developer tools in the ToolHQ developer category.

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Common HTML formatting errors and what they mean

When you paste messy HTML into a formatter and look at the output, certain patterns reveal underlying problems in the markup. Here are the most common issues and how to spot them.

Unmatched tags. An opening tag like <div> without a closing </div> will cause the formatter to either throw an error or produce unexpected nesting output. If the formatted result has an enormous indented block that seems to include everything that follows, a missing closing tag is likely the cause. Search for the tag in question and check that every opener has a corresponding closer.

Missing quotes on attributes. HTML attributes should always be quoted: <img src="photo.jpg" alt="A photo">. Unquoted attributes like <img src=photo.jpg> are technically parsed by browsers but are invalid and can break when the value contains spaces or special characters. After formatting, scan for attributes without surrounding quotes.

Improper nesting. HTML elements must close in the reverse order they were opened. <b><i>text</b></i> is incorrectly nested -- the inner <i> must close before the outer <b> closes. Correct nesting is <b><i>text</i></b>. Formatters may handle this inconsistently, and the visual indentation in the output will show unexpected jumps when nesting order is violated.

Self-closing tag mistakes. Void elements in HTML (elements that cannot have children) should not have a closing tag: <br>, <img>, <input>, <hr>, <meta>. Writing </br> or <input></input> is invalid HTML. In XHTML, these required a trailing slash (<br />), but standard HTML5 does not require the slash. Some formatters normalize these; others leave them as-is.

Before and after example:

Messy input:

<div><h1>Welcome</h1><p>This is a <strong>test page</strong> with a <a href=about.html>link</a>.<ul><li>Item one<li>Item two</ul></p></div>

Formatted output:

<div>
 <h1>Welcome</h1>
 <p>
 This is a <strong>test page</strong> with a <a href="about.html">link</a>.
 <ul>
 <li>Item one</li>
 <li>Item two</li>
 </ul>
 </p>
</div>

The formatted version reveals that the <a> tag was missing quotes on its href attribute, and that the list items were missing closing tags -- both are visible at a glance in the indented output.

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Frequently asked questions

Is my HTML sent to a server?

No. ToolHQ's HTML formatter processes your code entirely in your browser. Your code never leaves your device and is never sent to any server.

Will formatting change how the HTML renders in a browser?

No. Browsers treat whitespace between elements as equivalent to a single space or no space, depending on context. Adding indentation and line breaks does not change how the HTML looks in a browser.

Can I format HTML snippets, not just full pages?

Yes. The formatter handles anything from a single element to a full HTML document. Paste whatever HTML you have and it formats correctly.

Does the formatter validate HTML?

The formatter focuses on whitespace and indentation, not validation. It formats syntactically reasonable HTML but does not check for W3C validity or flag missing closing tags. Use an HTML validator for that.

What is the difference between formatting and minifying HTML?

Formatting adds whitespace and indentation to make HTML human-readable. Minifying removes all non-essential whitespace to make HTML as small as possible for delivery to browsers. They are opposite operations.

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The short version

HTML that's been minified, auto-generated, or copy-pasted without care is nearly impossible to read. ToolHQ's HTML formatter converts it to properly indented, structured markup in one click. Your code never leaves your browser.

No server, no account, no size limits.

For CSS minification, use ToolHQ's CSS minifier. For Markdown to HTML conversion, try ToolHQ's Markdown to HTML converter. Browse all developer tools at the ToolHQ developer category.

Format your HTML now

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