Free markdown validator

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Catch broken links, malformed front-matter, heading hierarchy issues, unclosed code fences, and the small mistakes that quietly hurt your docs and SEO.

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What we check

The mistakes that quietly hurt your docs.

Broken links and images

Empty URLs, missing anchor text, unencoded spaces, images with no alt — the small breakage that compounds across hundreds of pages.

Heading hierarchy

Missing H1, multiple H1s, level skips (H1 → H3) — search engines and screen readers expect sequential structure.

Front-matter integrity

YAML / TOML / JSON front-matter that opens but never closes is a top cause of broken static-site builds. We catch it before deploy.

Unclosed code fences

A ``` you forgot to close swallows the rest of the document. We tell you exactly which line opened it.

Table column mismatches

When the separator row has fewer columns than the header, the renderer silently misaligns rows. We flag the mismatch.

SEO-adjacent warnings

Missing image alt text, links with no anchor text, documents without an H1. The things Google notices, even if your renderer doesn't complain.

Validate your markdown.

Free. No signup. Runs entirely in your browser.