What This Tool Does
The Heading Structure Checker validates the heading tags in your HTML against a set of SEO and accessibility rules. It checks for the presence of exactly one H1, ensures no heading levels are skipped in the hierarchy, flags empty heading tags, warns about overly long headings, and highlights duplicate headings at the same level. Each check is scored to give you a single 0–10 quality rating for the document's heading structure, with a plain-English issue list and a full visual outline of the document hierarchy.
How to Use
- Paste your full HTML page source, or just the heading tags, into the input panel.
- Click Check Structure to run validation.
- Read the score banner — a green 9–10 means the structure is solid.
- Work through the issues list, fixing errors (red) before warnings (amber).
- Check the heading outline at the bottom to confirm the document reads as a logical hierarchy.
- Click Copy Report to share or save the full validation output.
Validation Rules
- Single H1: Every page should have exactly one H1 that names its primary topic.
- No skipped levels: The hierarchy must not jump from H2 to H4, for example — H3 must appear in between.
- No empty headings: Heading tags with no text confuse crawlers and screen readers.
- Heading length: Headings over 160 characters are flagged as too long to scan quickly.
- No duplicates: Two H2s with identical text create ambiguous navigation anchors.
- H1 appears first: The H1 should precede any H2–H6 to establish the document topic early.
Frequently Asked Questions
How is the heading structure score calculated?
The tool starts at 10 and deducts 2 points per error (missing H1, extra H1, skipped levels, empty headings) and 1 point per warning (very long headings, duplicate headings). The score is clamped at 0. A score of 9–10 is "Excellent", 7–8 is "Good", 5–6 is "Needs work", and below 5 is "Poor". Fixing all errors and warnings brings the score to a full 10.
What is the difference between this and the Heading Extractor?
The Heading Extractor is focused on extraction and visualisation — it takes HTML and outputs the full heading outline as an indented tree you can copy. The Heading Structure Checker is focused on validation — it runs structured rules against the heading hierarchy, produces a scored report, and gives you specific actionable issues to fix. Use the extractor to see what headings exist; use the checker to determine whether the structure is correct.
Why does skipping heading levels matter for SEO?
Search engines use heading hierarchy to infer topic relationships. An H3 is understood as a sub-topic of the H2 above it. If you jump from H2 to H4, the implied relationship breaks — Google may misparse the content structure and index the H4 as a stand-alone concept rather than a sub-point. More practically, users navigating by keyboard or screen reader rely on sequential heading levels to jump predictably through sections, and skipped levels create navigational dead zones. Fixing skipped levels is a low-effort, high-signal improvement.
Can I check just a partial HTML fragment?
Yes. The checker works on any input that contains heading tags — a full page, a<body> section, or even a bare list of heading tags pasted in without surrounding HTML. If you paste a fragment that starts at H2 (because the H1 lives in a parent template), it will flag a missing H1, which you can ignore in that context.