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format validator

HTML Validator (light)

Check HTML structure with HTMLHint rules—mismatched tags, casing, and basic issues—all client-side.

Results

Paste input and validate locally.
Status
Ready when you validate.
Details
Ready when you validate.

How to use this validator

  1. Paste the HTML snippet.
  2. Run validate to lint tag pairs/attributes.
  3. Fix reported lines (mismatched/uncased tags) and re-run.

Rules & checks

Runs HTMLHint client-side (no uploads).

Checks tag pairs, lowercase attributes, and basic structure issues.

Flags line/column of the first error and totals issues found.

Inputs explained

  • HTML content

    Paste markup snippets or templates. Keep to reasonably sized fragments for quick linting.

When to use it

  • Lint email templates before sending campaigns
  • Check CMS or WYSIWYG exports for broken tags
  • Validate snippet embeds before publishing

Common errors

  • Mismatched or unclosed tags
  • Uppercase attributes when lowercase is expected
  • Extra closing tags

Limitations

  • Lightweight HTMLHint rules; not a full W3C validator.
  • Does not fetch external assets or scripts.

Tips

  • Keep attributes lowercase to avoid warnings
  • Close non-void tags consistently to reduce rendering differences
  • Lint smaller snippets for speed; use full validators in CI for large documents

Examples

Valid

  • <div><p>Hi</p></div> -> Valid

Mismatched

  • <div><p>Hi</div> -> Flags closing tag mismatch

Deep dive

This HTML validator applies HTMLHint client-side to catch mismatched tags and casing issues before you publish.

Use it to lint snippets from CMS, WYSIWYG, or email templates without uploading markup.

FAQs

Is this a full W3C validator?
No. It applies HTMLHint rules for quick structural checks.
Do you send markup to a server?
No. Validation happens entirely in your browser.

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