HTML5 validator

Paste a document or component and review issues the client-side checker can see: unclosed tags, obvious attribute problems, missing structure.

It is not a substitute for the W3C Nu endpoint or a full accessibility audit. Use it before you commit a template.

How to Use

  1. Paste the HTML fragment or full document.
  2. Run the check and fix errors before warnings.
  3. Re-validate after each fix — one missing close can cascade.
  4. Follow with the meta tag generator and OG debugger once the page is deployed.

Key Features

  • Local markup scan
  • No upload of the page
  • No account
  • Pairs with SEO and OG tools after deploy

Frequently Asked Questions

Is this the official W3C validator?

No. It is a convenient in-tab check. Send critical templates to validator.w3.org as well.

Does valid HTML guarantee good SEO?

No. It just removes a class of crawl and a11y bugs.

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