Heading hierarchy checker. H1-H6 outline audit.
Paste HTML. We parse the H1-H6 outline tree, flag accessibility + SEO issues (multiple H1s, skipped levels, missing H1, empty headings) per WCAG 2.4.6 and Google's structured-content guidance.
Paste HTML. We parse the H1-H6 outline tree, flag accessibility + SEO issues (multiple H1s, skipped levels, missing H1, empty headings) per WCAG 2.4.6 and Google's structured-content guidance.
Sources used
- WCAG 2.4.6 — Headings and Labels
- WHATWG HTML — heading elements spec
- Google Search Central — Article structured data (heading guidance)
- MDN heading elements reference
Parsing happens entirely in your browser.
Privacy: parsing happens in your browser. Nothing is sent or logged.
Hierarchy is structure for machines.
Search engines use heading structure to understand page topic + content organization. A well-structured H1-H6 outline tells Google what the page is about (H1) and how subtopics relate (H2-H6 nesting). Pages with broken hierarchy are harder for Google to extract featured snippets and AI Overview citations from. Screen readers also use heading levels for navigation — broken hierarchy directly degrades accessibility per WCAG 2.4.6.
Three rules for heading hierarchy. One H1 per page (HTML5 allows multiple but best practice is one). Never skip levels — H1 → H2 → H3 in order; if visual hierarchy needs a step-down without semantic meaning, use a div with role-presentation. Aim for H1-H4 depth — H5/H6 usually signal the document should be split.
Tools in the same cluster: External Link Counter for link-mesh audit. Internal Link Counter for internal-link audit. SERP Preview Generator for the title + description preview.
Five answers.
Why does heading hierarchy matter for SEO?
Search engines use heading structure to understand page topic + content organization. A well-structured H1-H6 outline tells Google what the page is about (H1) and how subtopics relate (H2-H6 nesting). Pages with broken hierarchy (multiple H1s, skipped levels) are harder for Google to extract featured snippets and AI Overview citations from. Beyond SEO, screen readers use heading levels for navigation — broken hierarchy directly degrades accessibility per WCAG 2.4.6.
Is one H1 per page still required?
Strictly required by HTML5: no — multiple H1s are technically valid HTML5 spec. Best practice: one H1 per page. Google's John Mueller confirmed multiple H1s are not penalized, but a single H1 communicates page topic most clearly. Screen readers expect one H1 per landmark/section. The checker above flags pages with zero H1s (clear bug) or 3+ H1s (likely template error) but treats 2 H1s as a soft warning.
What's a 'skipped heading level'?
A skipped level is when the document jumps a heading rank — e.g., H1 directly to H3 with no H2 between. WCAG 2.4.6 requires headings descend in order (H1 → H2 → H3 → H4) without skipping. The fix is either using the correct semantic level (H2 between the H1 and H3), or using a div with appropriate ARIA role if the visual hierarchy is decorative. The checker above flags every skip with the line context for fast remediation.
How deep should heading hierarchy go?
H1-H4 covers most content needs. Long-form content (10,000-word guides) commonly uses H1-H5. H6 is rarely needed and often signals over-complication of structure. If you need H6, consider whether the document should be split into multiple pages. For SEO-friendly outlines, aim for 5-15 H2 sections per long-form page with optional H3 nesting under each — this matches the structure Google's featured-snippet extraction expects.
Does this tool save my data?
No. Parsing happens in your browser. Nothing is sent to any server.
Outline broken?
Our SEO engagements audit heading structure across templates, fix multi-H1 + skipped-level issues, and ship a single-H1-per-page rule that lifts featured-snippet eligibility.
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