Heading structure checker
Paste HTML to see the H1 to H6 outline and catch skipped or repeated levels.
FreeRuns in your browserNo signupUpdated 2026-11-05
Parsed in your browser with DOMParser; nothing is uploaded. Headings added later by JavaScript only show if you paste the rendered HTML from the browser's developer tools.
Reading the HTML…
About this tool
How it works and how to read the result.
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Technical SEO & performance
Faster pages, clean structure and better visibility in search.
See the serviceWhat it does
A heading structure checker lists every heading on a page, H1 to H6, in the order they appear and indented by level, so you can see the page's outline at a glance. It then flags the problems that make an outline hard to follow: no H1, several H1s, levels that skip (H2 straight to H4), empty headings, headings with the same text as an earlier one, and headings so long they read like paragraphs. Elements marked up with role="heading" and an aria-level are included too. The HTML is parsed in your browser and never uploaded.
How to use it
- Open the page in your browser and view its source (Ctrl+U on Windows, Cmd+Option+U on a Mac).
- Select all, copy and paste it into the box.
- Read the outline. Headings with a problem have an amber or red level badge and a note underneath.
- Fix the headings in your CMS or templates and paste the page again to confirm.
How to read the result
The sample is a short clinic page with ten headings: one H1, four H2s, three H3s, one H4 and one H5. The Issues stat shows 4.
The H1 check passes with "One H1". The first problem is "What is included", an H4 directly under the H2 "Prices and appointments": the outline skips H3. The second is an empty H3 under the FAQ heading, which shows in red because a screen reader would announce a heading with nothing in it. The third is a second H2 called "How whitening works", the same text as an earlier section, which makes the outline confusing to scan. The last is the footer's "Contact us" set as an H5 after an H2, which skips two levels; often the fix is to make it a paragraph styled to look like a heading.
The outline as text, at the bottom, can be pasted into a brief or ticket so a writer or developer can see the structure without opening the page.
A good outline is part of on-page SEO. Pair this check with the meta length checker for titles and descriptions, and the readability checker for the copy under each heading. For a full audit of templates and page structure, see our technical SEO service.
Questions
Frequently asked.
Is it wrong to have more than one H1?
It is not an HTML error, and search engines cope with it. The checker flags it as something to review rather than fix. One H1 that names the page, followed by H2s for the main sections, is still the clearest outline for readers, screen reader users and anyone editing the page later.
Why does skipping from H2 to H4 matter?
Screen reader users often jump between headings to understand a page, and the level tells them how sections relate. A jump from H2 to H4 suggests a missing section in between. The W3C's accessibility tutorials advise against skipping ranks. If you want a smaller heading, keep the right level and change its size with CSS.
Why are some of my headings missing?
The checker reads the HTML you paste. If your site adds content with JavaScript after the page loads, the page source will not contain it. Open the page, right-click, choose Inspect, then copy the html element from the Elements panel to get the rendered version, and paste that instead.
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