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Free developer tool

HTML Validator & Formatter

Validate HTML structure, detect missing tags, and format code for better readability. Check a live URL or paste your code on the left, then review the results on the right.

Working field

Paste HTML code or enter a URL.

Validation Result

Tags & structure verified.

Your validation results will show here once you validate a URL or HTML code.

This tool is best for checking HTML structure, missing tags, and SEO-ready markup.

Free HTML Validator, Formatter & Viewer

Keep your markup clean, valid, and well-structured for a professional user experience and better SEO. This tool keeps the workflow simple: validate or format on the left, supporting content below, and the sidebar on the left for popular and related tools.

URL & code validation

Validate live websites or paste HTML code for instant structural analysis.

Missing tag detection

Identify missing <html>, <head>, <body>, and <title> tags at a glance.

Format & beautify

Convert minified HTML into readable, properly indented code in one click.

SEO checker

Verify essential SEO elements are in place for better search rankings.

100% private

All processing happens locally, so your code never leaves your browser.

Mobile friendly

Validate HTML on any device with a fully responsive interface.

How it works

  1. Enter a website URL or paste your HTML code into the input field above.
  2. Click Validate to check the structure, or Format to beautify the code.
  3. Review results showing tag presence, page title, and size on the right.
  4. Click Copy HTML to grab the validated markup for your project.

Best practices

  • Always include a <!DOCTYPE html> declaration at the top.
  • Keep <html>, <head>, <body>, and <title> tags in place.
  • Format messy or minified code before debugging structure.
  • Remove comments and minify HTML for production speed.
  • Validate live URLs to catch issues on the rendered page.
  • Re-check your markup after each major edit before deploying.

Frequently asked questions

Is this tool free?

Yes. The HTML Validator is 100% free with no registration, limits, or hidden charges of any kind.

Can I validate a live URL?

Yes. Enter any website URL and the tool fetches and validates the HTML structure for you in seconds.

Does formatting affect website speed?

Formatting is for readability only. For production, use minified HTML with comments removed to improve load speed.

Is my data stored?

No. Everything runs locally in your browser, so we never store or share the code you paste or the URLs you test.

What is the DOCTYPE?

It tells browsers which HTML version to use. Always include <!DOCTYPE html> at the very top of your document.

Why do I need valid HTML?

Valid HTML ensures cross-browser compatibility, better SEO, and an improved user experience across every device.

What is the benefit of formatting HTML?

Formatting makes the code easier to read and debug. Proper indentation helps you quickly find structural errors.

Why should I remove comments from my code?

Removing comments reduces file size, leading to faster page loads. You can do this with the Remove Comments tool.

Can I validate a live website URL safely?

Yes. Just enter the URL and the tool fetches the HTML through a proxy to analyze its structure and validity.

Can I use this tool on a mobile phone?

Yes. The tool is fully responsive and works smoothly on smartphones, tablets, and desktop browsers.

How do I fix missing tags?

Format your code first so the clear structure highlights exactly where a closing or required tag might be missing.

Does it support HTML5?

Yes. It fully supports all modern HTML5 elements and semantic tags for accurate formatting and validation.

Can I remove comments from JavaScript too?

Yes. The Remove Comments tool works for HTML, CSS, and JavaScript files alike, keeping your output clean.

Want to improve your coding workflow? Try the Remove Comments tool to slim down production files, the HTML Formatter.