H1 and Heading Structure Checker (H1-H6)
Audit pasted HTML for multiple H1 tags, skipped heading levels and H1-H6 hierarchy problems.
Maximum 100,000 UTF-16 code units. The pasted HTML is inspected in source order; no live page is fetched.
Heading Hierarchy
Source order versus the rendered page
H1-H6 elements are parsed as HTML by DOMParser and listed in source order. Indentation represents heading level, not the actual DOM parent tree. For malformed HTML, the browser's repaired structure is inspected. Text inside scripts is not counted as headings; scripts are not run and their source nodes are not added to the page.
The example contains an H1, an H3, and an empty H2: expect two review warnings for the H1-to-H3 jump and the empty heading. Returning to a higher level, such as H3 to H2, does not by itself trigger a skipped-level warning.
A missing H1 or multiple H1s warrants review, but does not by itself prove ranking loss or an accessibility violation. A content fragment may omit the page's H1. Review the full-page context and whether headings accurately describe their sections.
CSS visibility, headings added after JavaScript runs, shadow DOM, iframes, and elements with ARIA role=heading are not evaluated. Hidden source headings may still be counted. No warnings do not establish full accessibility or SEO compliance; verify against the rendered page and screen-reader output. Heading Text Observations.
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TOOL GUIDE
What does the heading structure checker solve?
A sound heading hierarchy (H1-H6) matters for both accessibility and content clarity. This tool takes your page HTML, extracts the H1-H6 source order, and gives contextual review warnings for empty headings, skipped levels, and the number of H1s.
It does not generate content; it audits the heading outline of existing HTML. Source order and level transitions are reviewed; CSS visibility, the post-JavaScript DOM, and full accessibility are not checked.
How to use it
- Paste your page's HTML source or a content block.
- Review the indented H1-H6 order in the resulting hierarchy tree.
- Review the warnings in the context of the full page; a content fragment may leave the main heading outside.
When to use it
- Audit the heading hierarchy of a new page before publishing.
- Find multiple H1s and broken order on inherited or older pages.
- Confirm that the content outline is logical and easy to scan.
This tool processes supplied data in your browser. Text and inputs are analyzed on your device without being sent to a server.
Frequently asked questions
Can a page have more than one H1?
Technically yes, but a single H1 is usually recommended because it clearly signals the page's main topic.
Is skipping a heading level a problem?
Not skipping levels when moving to a lower section helps keep the structure understandable. Returning to a higher level can be normal. A warning on its own is not proof of an accessibility failure.
Should I put keywords in headings?
Where it is natural, yes. The priority is that each heading accurately summarizes its section rather than forcing keywords in.