📄 Online HTML Formatter

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Input HTML Code

Formatted Result

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About the HTML Formatter

Why Format HTML?

HTML code often becomes difficult to read and maintain after compression, transmission, or collaborative editing. A formatter automatically adds indentation and line breaks to make the structure clear, aiding debugging, review, and learning. This tool runs entirely in your browser with no data upload, ensuring both efficiency and security.

Core Features

Smart Indentation: Automatically calculates indentation based on tag nesting. Supports 2 spaces, 4 spaces, and Tab.

Attribute Line Breaks: Optionally place each attribute on its own line, ideal for complex tags with many attributes.

Self-Closing Tag Handling: Automatically recognizes self-closing tags such as img, br, and input, without adding extra indentation.

Comment Management: Choose to keep or remove HTML comments for flexible output control.

Live Preview: When enabled, formatting happens automatically as you type.

How It Works

This tool uses a regex-based HTML tag parser to decompose input code into tags, text, and comments. It maintains a tag stack to track nesting depth and combines it with a self-closing tag whitelist to compute accurate indentation. The attribute line break feature parses each tag's attribute list and restructures it.

How to Use

Step 1: Input HTML. Paste or type the HTML code you want to format into the input area. The tool supports standard HTML and custom tags.

Step 2: Choose Options. Select your preferred indent width. Enable "Attribute Line Break" for tags with many attributes. Check "Remove Comments" to strip HTML comments. Enable "Live Preview" for automatic formatting on every keystroke.

Step 3: Format and Copy. Click the "✨ Format" button to see the result. Click "📋 Copy Result" to copy to clipboard, or "💾 Download as .html" to save locally.

Use Cases

Web Development & Debugging: HTML retrieved from network requests or third-party sources is often minified. Use this tool to quickly restore it to a readable format for easier understanding and modification.

Code Review & Teaching: Well-formatted HTML with clear indentation is easier for team members to review. In teaching scenarios, proper indentation helps students understand HTML's hierarchical nesting.

Template Generation & Cleanup: After generating HTML with template engines (such as EJS, Pug, or Handlebars), you may want to format the output to match your team's code style.

Frequently Asked Questions (FAQ)

Does HTML formatting change the page structure?

No. This tool only adjusts indentation, line breaks, and whitespace. It does not modify any tags, attributes, or text content. The DOM structure remains identical before and after formatting.

What indentation options are supported?

Three styles are supported: 2 spaces, 4 spaces, and Tab. Choose the one that matches your team's coding standards or personal preference.

What is self-closing tag special handling?

Self-closing tags (such as img, br, input, meta, etc.) do not increase indentation levels. The tool automatically recognizes these tags, ensuring they stay at the same indentation level as sibling tags.

What does the attribute line break feature do?

When enabled, each attribute is placed on its own line, making the code more readable. This is especially useful for complex components with many data or ARIA attributes.

Is my HTML data uploaded to a server?

No. This is a pure frontend application. All processing happens locally in your browser, and no data is ever uploaded to a server. You can safely process sensitive HTML code.

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`; updateInputStats(); formatHTML(); } inputText.addEventListener('input', () => { updateInputStats(); if (livePreviewChk.checked) { try { resultText.value = doFormat(inputText.value.trim(), getOptions()); } catch (e) {} } }); indentSizeSel.addEventListener('change', () => { if (livePreviewChk.checked) formatHTML(); }); attrNewlineChk.addEventListener('change', () => { if (livePreviewChk.checked) formatHTML(); }); removeCommentsChk.addEventListener('change', () => { if (livePreviewChk.checked) formatHTML(); }); updateInputStats();