HTML Linter
Lint HTML for missing DOCTYPE, unclosed tags, and unexpected closing tags. Paste your HTML and get instant feedback. Catch errors before browsers guess wrong — free, local, no signup.
How to Use the HTML Linter
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Frequently Asked Questions
What does the linter check?
Missing DOCTYPE declaration, unclosed tags, unexpected closing tags, duplicate attributes, deprecated elements, and accessibility issues.
Does it validate HTML5 syntax?
Yes. The linter checks HTML5 DOCTYPE, valid element nesting, required attributes, and semantic structure compliance.
Can it fix issues automatically?
No. The linter identifies issues with line numbers and descriptions. You must manually edit the HTML to fix reported problems.
Does it check for accessibility?
Basic accessibility checks include missing alt attributes on images, missing form labels, and heading hierarchy issues.
Is my HTML data stored?
No. All linting happens locally in your browser. No HTML data is transmitted.
Which tags does it ignore, and what do the messages look like?
7 tokens skip the open/close stack: br, hr, img, input, meta, link and !DOCTYPE (DOCTYPE presence itself is checked case-insensitively). Mismatches report Unexpected closing tag, leftovers report Unclosed tags with the tag list, clean docs print No issues found, and the toast counts findings as Found N issue(s).
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Last updated October 2026