Heading Structure Checker
Paste your page HTML or Markdown and see the H1 to H6 outline the way a crawler does, with missing H1s, skipped levels and empty headings flagged instantly.
Your HTML
Checks
Outline
Your headings are the outline of your page, and a broken outline hurts both the people using a screen reader and the crawlers trying to understand your content. This free checker reads the H1 to H6 tags in your HTML, or the # levels in your Markdown, and shows the hierarchy exactly as a machine sees it, flagging a missing or duplicate H1, a skipped level and any empty heading. It is built for content writers, developers and SEOs who want to confirm a page has a clean, logical structure before it ships, not after an audit flags it.
How to use it
Paste your HTML or Markdown
Drop in the rendered HTML of your page, or Markdown headings where # is H1 and ## is H2. The outline builds live as you paste, with nothing to send.
Read the outline
Each heading appears at its real nesting level with an H1 to H6 badge, so you can see the structure at a glance and spot a level that sits deeper or shallower than it should.
Fix the flagged checks
The checks panel calls out a missing H1, multiple H1s, a skipped level and empty headings. Correct them in your source, paste again, and confirm the outline is clean.
Why it's useful
Sees the structure, not the styling
The checker reads heading tags, not visible font sizes, so it shows the outline a crawler and a screen reader actually encounter, catching problems a page can hide behind CSS that makes an H3 look like an H1.
Catches the errors audits flag
A missing H1, a jump from H2 straight to H4, a heading with no text: these are the exact issues accessibility and SEO audits report. Finding them here means fixing them before they cost you, not after.
Nothing leaves your browser
Parsing happens entirely client-side. Your HTML, including unpublished pages and client work, is never uploaded or stored, so you can check anything without signing in.
Why heading hierarchy matters
Headings are the outline, not the decoration
Headings are the outline of your page, and two very different audiences rely on that outline. People using a screen reader navigate by jumping from heading to heading, so a clean hierarchy is how they move through a page without reading every word; a page whose headings are chosen for how big they look leaves them lost. Search engines use the same hierarchy to understand how your sections relate and which topics a page actually covers, which feeds directly into whether you get found and get cited for them. A tidy H1 to H2 to H3 structure is readable by both machines and assistive technology at once, and the same outline works whatever language you publish in, which matters when Otorank is tracking your visibility across 150+ languages.
One H1, and never skip a level going down
Use one H1 per page, naming what the whole page is about, then nest from there: an H2 for each main section, an H3 for a sub-point inside that H2, and so on down. The rule that trips most pages up is skipping a level on the way down. An H2 followed directly by an H4 leaves a gap in the outline, and assistive technology reads that gap as a missing section, as if a whole subsection vanished. Jumping back up the levels is fine and expected, because that simply closes a branch and starts the next section. The checker flags a skipped level the moment it sees one, so you can tell a genuine structural gap from a deliberate return to a higher level.
Keep style and level as separate decisions
If an H3 looks too big, change its CSS, do not promote it to an H2 to shrink it or demote a heading to fit a visual. The level should reflect where the content sits in the structure; the appearance is a styling concern handled in your stylesheet. Mixing the two is how outlines quietly break while the page still looks right to a sighted reader.
Checking what actually ships
This checker reads the heading tags, not the visible font sizes, so it sees the structure a crawler sees rather than the one your layout implies. That distinction matters because a page can look perfectly ordered while its underlying markup is a mess of skipped levels and styled-up paragraphs. Paste the rendered HTML of a live page to audit exactly what reaches search engines and assistive technology in production. If you write in Markdown, paste that too: a single # becomes an H1, ## becomes an H2, and the same rules about one H1 and no skipped levels apply. Checking the real output, not the draft in your head, is the only way to be sure the outline you intended is the outline you actually shipped.
They use Otorank
Questions
How many H1s a page needs, what counts as a skipped level, and why the checker reads tags rather than font sizes.
One. The H1 names what the whole page is about. Multiple H1s blur that signal for crawlers and assistive technology, and no H1 at all leaves the page without a clear top-level topic; the checker flags both.
Jumping more than one level deeper, such as an H2 followed directly by an H4. It leaves a gap the outline reads as a missing section. Going back up the levels is fine; it just closes a branch.
Both. Paste rendered HTML and it parses the H1 to H6 tags; paste Markdown and # becomes H1, ## becomes H2, and so on. The same structural rules apply to each.
They help search engines understand your structure and what each section covers, which supports getting found and cited for those topics. They are one honest signal among many, not a ranking lever on their own.
No. All parsing happens in your browser; nothing is uploaded or stored, so you can check unpublished pages and client work safely.