Heading Structure Checker
Review HTML heading hierarchy, H1 usage, skipped levels, duplicates, empty headings, and outline structure.
Paste rendered HTML, a copied page section, Markdown headings, or a simple outline. The analysis runs locally in your browser.
Options
Checks H1 count, empty headings, duplicate text, skipped levels, and an optional heading-length heuristic. The score is a local review aid, not a Google ranking score or WCAG conformance result.
Output
Heading structure output will appear here.
Read the outline as structure, not as an SEO score
Heading levels describe how sections relate to one another. They help people scan a page and give screen-reader users a fast way to move between sections. A sensible hierarchy matters more than forcing a particular number of headings.
Google explicitly says there is no magical ideal number or strict ordering of headings for Search. The hierarchy checks here are mainly an editorial and accessibility review, not a ranking test.
What a skipped level really means
Moving from H2 directly into H4 can make the hierarchy harder to follow because an H3-level section appears to be missing. Moving back from a deeper subsection to a higher level is normal when a subsection ends.
H1 count needs context
A single descriptive H1 is a clear convention for most pages, but multiple H1 elements are not automatically an SEO failure. Review whether the main topic and section boundaries remain obvious to people and assistive technology.
Three input modes, three different assumptions
HTML: reads actual H1-H6 elements. The hidden-heading option recognizes thehidden attribute,aria-hidden="true", and common inline display/visibility styles. It cannot evaluate external stylesheets or every runtime visibility rule from pasted source.
Markdown: reads ATX headings using one to six hash characters and ignores headings inside fenced code blocks.
Plain outline: accepts explicit labels such as H2: or infers levels from two-space indentation. That inference is a convenience, not a document standard.
Treat length and duplicate warnings as editorial prompts
WCAG and Google do not publish a maximum heading character count. The strict, balanced, and relaxed length thresholds are local heuristics for spotting headings worth rereading. Repeated wording can also be legitimate when the surrounding sections make the meaning clear.
Compare the outline with the rendered page
Pasted source cannot reveal every heading created by client-side rendering, component state, CMS transformations, or CSS. When a page changes after JavaScript runs, compare the result with the rendered DOM and test keyboard or screen-reader heading navigation as well.
Standards and search guidance
W3C WAI explains how heading ranks communicate page organization and recommends avoiding skipped ranks when opening subsections. Google's SEO Starter Guide recommends headings that help users navigate while also noting that Search does not require a perfect semantic order.