What "basic checks" honestly means
This is a first-pass checker, not the full W3C validator or a production linter: it catches the errors that break layouts and kill scripts silently — the unclosed <div> that swallows a page, the "colr:" a browser ignores without a word, the missing } three hundred lines up. It does not judge whether your HTML is semantic, whether your CSS values are sensible (color: 12px passes), or whether your JavaScript logic is right. Run it before the deep tools, the way you proofread before submitting: the cheap pass catches most of the pain.
Frequently Asked Questions
Is my code uploaded anywhere?
No. Every check runs in JavaScript on this page — paste proprietary code safely.
It says no problems, but my page still looks wrong.
Valid code can still be the wrong code — a checker verifies structure, not intent. Check the layout rules themselves (sizes, positioning, loading order) next.
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