MCP HTML Validator MCP Tool
validate_html(url) — ask an AI assistant to validate a page's HTML: deprecated elements, missing alt text, unlabelled form controls, duplicate ids, and more.
validate_html(url)
Fetches a public page and runs it through the same checks as the HTML Validator web tool — deprecated elements, missing image alt text, form controls without an accessible label, duplicate ids, heading structure, and more.
Requires a Pingfloat API key. See MCP Server setup if you don't have one yet.
Try it
Validate the HTML on https://example.comThe assistant calls validate_html and returns a score, grade, and a list of error/warning/info issues found.
Parameters
| Parameter | Type | Description |
|---|---|---|
url | string, required | The public page URL to validate. |
What it checks
- Deprecated or non-standard elements
- Images missing
alttext - Form controls (
input,select,textarea) with no accessible label - Duplicate
idattributes - Heading structure (missing or multiple
<h1>) - Unbalanced tags and other structural issues
Frequently asked questions
Does it check pages behind a login?
No — it fetches the page as a public, unauthenticated request, the same as a search engine crawler would see it.
Is there a limit on how many times I can call it?
10 per hour on a free account, 50 per hour on Free+ — shared with the other check and QR tools, tracked per API key.