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HTML Validation

Open in QuickMonitoring→ Sites → [Your Site] → Scans → Validation

QuickMonitoring runs every crawled page's HTML through W3C validation. Invalid HTML causes unpredictable browser rendering and blocks accessibility tools. This check catches the errors that manual testing misses — mismatched tags, deprecated attributes, missing required elements.

What you'll see​

Go to Sites → your site → Validation (sidebar) → filter by "HTML".

Results from the W3C validator, tied to specific page URLs:

  • Errors — Invalid markup that browsers have to guess at
  • Warnings — Deprecated or non-standard usage
  • Info — Best-practice suggestions

Each issue includes the specific rule violated and, where possible, the element or tag responsible.

How to use it​

  1. Run a scan
  2. Go to Sites → your site → Validation (sidebar) → filter "HTML"
  3. Review W3C HTML errors per page
  4. Click any error to see the specific line or element flagged

Start with pages that have high error counts — they often have a structural problem (broken template include, unclosed tag) causing a cascade of downstream errors.

Pass condition​

✅ You've earned this achievement when the Validation section shows HTML validation results — an error list or a "no HTML errors" confirmation — for your scanned pages.

Common issues​

  • Hundreds of HTML errors from a single page — Almost always caused by one mismatched or unclosed tag early in the document. Fix the root problem in your template, not individual instances. The validator stops understanding the structure after the first bad tag, so the error count is misleading.

  • W3C errors in third-party widget HTML — Chat widgets, booking forms, and ad scripts often inject invalid HTML. These are real errors, but they come from code you don't control. Lower priority than your own markup — but worth flagging to the widget vendor.

  • Errors on pages that look fine in Chrome — Chrome's HTML parser is extremely forgiving. It silently fixes broken markup. The W3C validator catches what Chrome corrects for you. "Looks fine" ≠ "is valid".

  • Deprecated attribute warnings — Common on older CMS themes using HTML4-era attributes. Not breaking today, but a sign the theme needs updating. Flag these as tech debt.