About this tool

This page opens the HTML validator preloaded with a small, deliberately clean document: a doctype, a head with a charset and title, and a body with a header and a paragraph. Every tag that needs a closing tag has one, in the right order, so the validator reports a pass the moment the page loads.

It exists as a reference point. Before you paste in a real template or a page you're debugging, this is what a passing result actually looks like — useful for confirming the tool works as expected, or for comparing structure against a page that is failing for reasons you can't immediately spot.

Edit the sample directly in the box below: remove a closing tag, swap the order of two elements, or drop a quote from an attribute, and watch the validator's status flip from valid to invalid with the exact line called out.

Example. The fragment <div><p></div> fails on the closing div, because the checker still expects </p> from the p that was opened.

Limit. Void tags such as img, br, meta, and input need no close tag. The checker matches tag names and quote marks. It does not apply the HTML5 content model or require attributes such as alt.