HTML Formatter
Beautify and tidy HTML markup for readability.
HTML Formatter
What This Tool Does
- HTML Formatter beautifies and validates HTML markup with consistent indentation and readable nesting.
- Detect syntax errors, correct attribute formatting, and prepare clean HTML for commits, reviews, and templates.
Usage
- Paste HTML markup into the editor—from snippets to full documents.
- The formatter validates structure and highlights errors in malformed markup.
- Adjust indentation level if needed and review the formatted output.
- Copy or download the beautified HTML for templates, documentation, or version control.
Examples
- Beautify generated HTML from template engines before committing.
- Normalize copied markup from browser DevTools for use in your project.
- Clean HTML scaffolding from CMS exports before review.
- Format email template HTML for readability in code review.
Limitations
- Severely invalid markup may still require manual correction after beautifying.
- Template-engine directives can be reformatted in ways that need review.
Common Mistakes
- Unquoted attributes: <div class=container> fails; must be <div class="container">. All attributes must have quoted values.
- Mismatched tags: <div><p></div></p> is invalid nesting. Ensure closing tags match the most recent opening tag.
- Forgetting closing tags: <p>Text<p>More closes first <p>, not both. Self-closing elements like <img> do not need explicit close.
- Invalid attribute names: Attributes must start with a letter and can contain alphanumerics and hyphens (not underscores).
- Boolean attributes incorrectly quoted: <input disabled="false"> is still disabled. Omit the attribute or use <input>. true/false are treated as attribute names, not values.
- Entity misuse: Using < instead of < in content breaks parsing. Always use entities for special characters.
Technical Reference Guide
- Element: Opening and closing tags. Example: <div>Content</div>. Opening tag may have attributes.
- Self-closing tags: Void elements that have no content. Example: <img>, <br>, <input>, <meta>. May use /> but not required in HTML5.
- Attributes: Key-value pairs on opening tags. Example: <a href="url" class="link">. Values must be quoted.
- Text nodes: Plain text between opening and closing tags. Example: <p>Hello World</p>.
- Comments: <!-- comment text -->. Useful for documenting sections. Note: do not use -- within comments.
- Character references: & entities for special chars. Example: < for <, for space, © for ©.
- Doctype: <!DOCTYPE html> declares HTML5. Must be the first line.
- Scripts/Styles: <script> and <style> tags hold code blocks that should be treated as content, not formatted as markup.
Specifications & Standards
FAQ
Will formatting change element behavior?
No. Formatting changes whitespace and indentation only. Semantic meaning is preserved if markup is valid.
Can malformed HTML be auto-fixed?
The formatter highlights issues and repairs minor problems, but structural errors (mismatched tags, invalid nesting) require manual fixes.
How is inline content like <script> handled?
Script and style content is preserved as-is to avoid breaking embedded code. Use a dedicated JavaScript or CSS beautifier for those blocks.
Are HTML comments preserved?
Yes, comments are preserved and formatted with surrounding elements.
Can whitespace-sensitive layouts be affected?
Formatting adds newlines and indentation. If layout relies on inline whitespace (flex gaps, etc.), review output.
What about SVG or XML in HTML?
SVG is formatted as HTML markup. For strict XML validation or XHTML, use dedicated XML tools.
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