Question 1

What HTML errors does ValidateHTML check for?

Accepted Answer

ValidateHTML checks for unclosed tags, missing required attributes, deprecated HTML elements, incorrect tag nesting, missing DOCTYPE, invalid attribute values, accessibility issues, and more.

Question 2

Is ValidateHTML free to use?

Accepted Answer

Yes, ValidateHTML is completely free. You can validate unlimited HTML code snippets and URLs at no cost. No registration required.

Question 3

How is the HTML quality score calculated?

Accepted Answer

Your score starts at 100 and each distinct error type multiplies it by 0.85, so one error scores 85, two score 72, and the number keeps moving no matter how many you have. Each distinct warning type costs 3 points, capped at 15 in total, so best-practice advice can never drag valid HTML below a B. Repeated occurrences of the same rule don't stack. Grades: A (90-100), B (75-89), C (50-74), D (25-49), F (below 25).

Question 4

Does HTML validation affect SEO?

Accepted Answer

Yes. Clean markup improves crawlability, reduces rendering errors, and ensures search engines can properly parse your content. Valid HTML also improves accessibility, which is increasingly important for SEO.

Question 5

How is ValidateHTML different from the W3C Validator?

Accepted Answer

ValidateHTML offers a modern interface with a 0-100 quality score, letter grades, severity filters, copy/export features, and instant results. The W3C Validator is the official standard checker but has a dated interface and no scoring system.

Question 6

Can I validate HTML from a live website?

Accepted Answer

Yes. Switch to URL mode, enter any website address, and ValidateHTML will fetch the page HTML and validate it for you. This works with any publicly accessible URL.

Question 7

What is a good HTML quality score?

Accepted Answer

A score of 90-100 (Grade A) means your HTML is clean and follows best practices. 75-89 (Grade B) is good with minor issues. Below 50 (Grade D or F) indicates significant problems that should be fixed.

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