Validate heading hierarchy: missing H1, heading jumps, duplicates, over-long headings. Structure score 0–100.
Paste Markdown to validate its heading structure.
Free Markdown Structure Validator checks your heading hierarchy for problems: missing H1, multiple H1s, heading level jumps, duplicate headings, and over-long headings. It displays a visual heading outline tree and returns a structure score from 0 to 100.
Privacy: This tool runs entirely in your browser. Your text is never uploaded, logged, or cached. Close the tab and it's gone. Verify in DevTools → Network: zero requests fire.
A clean heading hierarchy matters for accessibility and SEO. Checking it should not require installing a linter. The validator runs 100% client-side.
| Input | Output | Typical size | Speed | Login needed |
|---|---|---|---|---|
| Markdown (.md) | Heading outline + score + issues | Any document size | < 10 ms | No |
Here's what this free tool does in detail — every feature is built to solve real problems, runs entirely in your browser, and is free forever.
The validator displays every heading as an indented tree, making it easy to see the document hierarchy at a glance. Each entry shows the heading level, text, and line number.
To extract headings as a list, use the Headings Extractor.
When a heading skips a level (e.g., H2 followed by H4), it breaks the logical outline. Screen readers announce heading levels to users, so jumps create a confusing experience. The validator flags every jump with the exact line number.
Duplicate heading text at the same level is flagged as informational -- it may be intentional but often indicates copy-paste errors. Headings over 80 characters are also flagged, since long headings hurt readability and SEO.
For broader SEO analysis, try the SEO Checker.
The score starts at 100 and deducts 25 for errors (missing H1), 10 for warnings (heading jumps, multiple H1s), and 3 for informational issues. A score of 80+ means the structure is solid; below 60 suggests significant reorganization is needed.
For accessibility-focused validation, see the Accessibility Auditor.
Paste any Markdown document into the input, or click Load example.
The heading tree and issue list update instantly as you type.
Click Copy report for a plaintext summary including the heading outline.
Validate heading hierarchy before publishing to a docs site.
Catch heading jumps and missing H1 before pushing to GitHub.
Use the score as a gate for heading structure quality.
Ensure heading levels are sequential for screen reader users.
Verify proper H1-H6 hierarchy for search engine crawlers.
Yes. Free forever, no account required.
Missing H1, multiple H1s, heading jumps, duplicate headings, and headings over 80 characters.
Starts at 100, deducts 25 per error, 10 per warning, 3 per info issue.
When a heading skips a level, like H2 followed by H4. Levels should be sequential.
No. Runs 100% in your browser.