Paste your page's HTML and instantly see its heading outline — every H1 to H6 as a clean, indented tree. The checker flags missing or multiple H1s, skipped heading levels, and empty headings, so your document structure is logical for readers, screen readers and search engines. 100% in your browser — nothing is uploaded or stored.
🔒 Everything runs in your browser. Your HTML is never uploaded, logged or stored.
The Heading Structure Checker turns your page's HTML into a clear, indented outline of every heading from H1 to H6, so you can see your document's structure the way a screen reader or search engine does. A logical heading hierarchy — one H1, then H2 sections, then H3 subsections — helps readers scan, helps assistive technology navigate, and helps Google understand how your content is organised. This tool extracts your headings in document order, draws them as a tree, and flags the common problems: a missing or duplicated H1, skipped levels like an H2 jumping straight to an H4, and empty headings that carry no text.
It is part of the SERP & Content Analysis group in our free SEO Toolkit. Pair it with the Title Tag Length Checker and Meta Description Length Checker to perfect the parts that show in search, the Keyword Density Analyzer to balance terms across those headings, the Word Count & Reading Time Analyzer to size the content beneath them, and the Meta Tag Analyzer to audit the rest of the page's tags. Everything runs in your browser — your HTML is never uploaded or stored.
Every heading, every level, every issue.
Headings are drawn as an indented, colour-coded outline by level.
Flags a missing H1 or more than one H1 on the page.
Catches jumps like H2 straight to H4 that break the hierarchy.
Your HTML is parsed in your browser — nothing leaves your device.
From raw HTML to a clean outline.
Drop in your page source or body markup.
The outline tree builds instantly.
See H1, skip-level and empty-heading flags.
Adjust until the verdict turns green.
One H1, descending one level at a time, no gaps.
A heading structure checker reads the HTML of a page and lays out its headings — the H1 through H6 tags — as an indented outline, so you can see at a glance how the content is organised. Headings are not just big bold text; they are the structural skeleton of a document. Screen readers let users jump between them, search engines use them to understand topic hierarchy, and human readers scan them to find what they need. When headings are out of order, duplicated or empty, that skeleton breaks. This tool exposes the structure and points out exactly where it goes wrong. It is part of the SERP & Content Analysis group in the SEO Toolkit.
Think of headings like a table of contents that you never have to write by hand. The H1 is the title of the whole page, H2s are its main sections, H3s are subsections within those, and so on. This nesting should be consistent: you descend one level at a time and only go back up when a new section begins. Get it right and the page reads logically for everyone; get it wrong and assistive technology announces a confusing outline while search engines struggle to map your topics.
Screen-reader users navigate by heading — a broken outline strands them.
Clear hierarchy helps search engines understand your topic structure.
Readers skim headings first — logical ones keep them on the page.
Well-structured sections are easier for Google to lift into rich results.
Three issues account for most heading problems, and the checker flags all of them. A missing or multiple H1 leaves the page without a single clear main topic — the convention is exactly one H1 per page. A skipped level, such as an H2 followed directly by an H4, creates a gap in the outline that confuses screen readers expecting the next step down to be an H3. An empty heading — a heading tag with no text, often left behind by a page builder or used purely for styling — announces a blank entry in the outline and wastes a structural signal. The tool marks each of these clearly so you know what to fix.
It uses the browser's built-in DOMParser to turn your pasted text into a real document, then collects the h1 to h6 elements in the order they appear. Because it parses rather than guesses with patterns, it handles nested markup, attributes and inline tags inside headings correctly, and reads the visible text the way a browser would.
One H1 per page is the long-standing, safest convention: it gives the page a single clear title. The HTML5 outline algorithm once allowed multiple H1s inside sections, but browsers and assistive technology never fully adopted it, so a single H1 remains the reliable choice. The checker treats one H1 as ideal and warns on zero or more than one.
Screen-reader users navigate by heading level and expect the outline to descend one step at a time. Jumping from H2 to H4 implies a missing H3 section, which can make them think content was skipped or mis-structured. Visually the text may look fine, but the underlying outline is broken — which is exactly what this tool surfaces.
No. Parsing and analysis run entirely in your browser with JavaScript, and the tool never makes a network request with your markup. Nothing you paste is uploaded, logged or stored, so it is safe for unreleased pages and confidential client projects.
Check the outline before a new page or article goes live.
Verify a logical heading order for screen-reader users.
Catch empty or mis-levelled headings left by visual editors.
See how heading nesting builds a document outline.
Use the Heading Structure Checker with these tools from the SEO Toolkit: perfect the search-visible parts with the Title Tag Length Checker and Meta Description Length Checker, balance terms across headings with the Keyword Density Analyzer, size the content with the Word Count & Reading Time Analyzer, check clarity with the Text Readability Scorer, audit the full page with the Meta Tag Analyzer, and preview the result with the SERP Snippet Preview.
Anyone who cares about clean, accessible structure.
Everything about heading structure.
It reads the HTML you paste and lays out every heading from H1 to H6 as an indented outline tree, then flags structural problems: a missing or duplicated H1, skipped levels such as an H2 jumping to an H4, and empty headings. It gives you a clear picture of how your page is organised.
Yes, completely. There is no cost, no sign-up and no limit on how many pages you check. The tool runs entirely in your browser, so there are no server costs and nothing to pay for.
One H1 per page gives the document a single clear title that describes its main topic, which both search engines and screen-reader users rely on. While the HTML5 specification once permitted multiple H1s inside sections, browsers and assistive technology never adopted that model, so a single H1 remains the safest, clearest convention.
A skipped level happens when the hierarchy jumps more than one step down — for example an H2 followed immediately by an H4, with no H3 between them. It implies a missing subsection and confuses screen-reader users navigating by level. Headings should descend one step at a time, and the tool marks any heading that skips.
An empty heading is a heading tag containing no visible text, often left behind by page builders or used purely for spacing. To a screen reader it announces a blank entry in the outline, and to a search engine it is a wasted structural signal. The checker counts empty headings so you can remove or fill them.
No. Parsing and analysis run entirely in your browser using the built-in DOMParser, and the tool never sends your markup over the network. Nothing you paste is uploaded, logged or stored, so it is safe for unreleased pages and confidential client work.
Either works. You can paste the complete page source from View Source, or just the body or a section of markup from your editor. The tool finds and lists every heading element wherever it appears, in the order it occurs in the document.
Headings help search engines understand how your content is organised and which topics are primary versus supporting, which supports relevance and can improve eligibility for featured snippets. They are not a heavyweight ranking factor on their own, but a clear, logical hierarchy is part of well-structured, helpful content.
Screen-reader users can pull up a list of a page's headings and jump straight to the section they want, much like a sighted user scanning the page. This only works if the headings are present, in order and meaningfully labelled, which is exactly what the checker helps you confirm.
In most browsers you can right-click the page and choose View Page Source, or open developer tools and copy the rendered HTML. In a CMS or page builder, switch to the code or HTML view of your content. Paste whatever you copy and the tool will extract the headings.
Yes. The checker is fully responsive, so you can paste HTML and review the outline from a phone or tablet. The tree, the heading counts and the issue list all display and scroll cleanly on small screens just as they do on desktop.
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Paste your HTML and see a clean H1–H6 outline with instant flags for missing H1s, skipped levels and empty headings — free, private and instant in your browser.
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