Heading Structure Analyzer
Inspect the H1–H6 outline in HTML source. Find missing or empty headings, skipped levels, repeated text and headings marked hidden—all without rendering or executing pasted markup.
| Level | Heading text | ID | Line |
|---|
Check heading order and readable text
Review document structure alongside the source rather than judging it by font size.
The tool lists H1 through H6 elements in source order and flags a missing H1, empty heading text, skipped levels, repeated text and headings with their own hidden or aria-hidden="true" attribute. It also reports if a heading was not explicitly closed in the pasted source.
A skipped-level warning is a review hint, not a complete SEO score. For example, moving from H2 directly to H4 may make the outline harder to follow; the right structure depends on the document.
HTML is scanned as source text in a worker. The page does not use DOMParser, insert markup into the document, execute scripts, render CSS or fetch linked resources. Script, style, template and noscript contents are ignored.
This is not a full HTML validator. It cannot calculate computed visibility, detect hidden ancestors, or interpret every malformed HTML edge case. It is intended as a fast outline review.
How to analyze a heading outline
Paste the page source, inspect the outline and review any hints.
Paste or open HTML
Use a source snippet, drop a local file, or choose Open HTML file.
Run the analysis
Small inputs update automatically. Large input requires a manual run.
Review the outline
Check heading order and findings, then copy the outline or download JSON.
Frequently asked questions
It lists H1–H6 elements in source order and flags missing H1s, empty text, skipped levels, repeated heading text and headings marked hidden or aria-hidden.
No. It scans source, not computed layout or CSS. It can spot a heading's own hidden or aria-hidden attribute, but cannot determine visibility caused by styles or hidden ancestors.
No. The tool scans text in a worker and never inserts markup into a live page. Script, style, template and noscript contents are skipped, and external resources are not fetched.
Not as a strict HTML validity rule. Multiple H1s are reported as information so you can review whether the page topic and outline are clear.
The maximum HTML source size is 1 MiB. Automatic analysis pauses on large input; click Analyze headings to run manually.