Heading Structure Analyzer - H1–H6 Outline Checker

How to use this tool

1. Paste your HTML. Copy your page's HTML source and paste it into the text area.
2. Review the outline. See the heading tree with indented levels and any detected issues.
3. Fix the issues. Review missing or repeated H1s, skipped levels, empty headings, and the informational long-heading warnings.

Why heading structure matters for SEO

Search engines and readers use heading tags to understand the hierarchy and topics of a page. An H1 usually introduces the page topic, H2s divide major sections, and H3s organize subsections within those sections. A clear outline makes long pages easier to scan and gives search systems useful context, although headings alone do not guarantee rankings.

Paste HTML copied from your own page source or browser developer tools. The analyzer uses the browser’s HTML parser to find H1 through H6 elements in document order, then reads their text content and collapses whitespace. Comments and text inside scripts are not heading elements, so they do not appear in the outline. All analysis happens in the browser; the pasted HTML is not uploaded.

Common heading mistakes

• Multiple H1 tags - this checker flags repeated H1s because it expects one page-level title. HTML sectioning can make multiple H1s intentional, so review the context.
• Skipped levels - jumping from H1 to H3 can make the hierarchy less clear to readers. The analyzer reports this as a warning; a skipped level alone does not prove a WCAG failure.
• Empty headings - a heading with no readable text leaves an unhelpful entry in the outline and is reported as an error by this checker.
• Missing H1 - pages without an H1 miss a useful page-level label, so this checker reports a warning.
• Long heading text - a heading over 14 words or at least 70 characters gets a soft SEO warning. These thresholds are practical prompts for review, not accessibility rules.

Outline hierarchy rules

• One H1 per page: a single H1 can serve as the page title and identify its primary topic. This checker flags repeated H1s; HTML sectioning can make multiple H1s intentional, so consider the page structure and your site's convention.
• H2s for major sections: each H2 represents a top-level section of the page's content.
• H3s for subsections: H3s nest inside H2 sections. Never skip from H2 to H4.
• Keep the outline coherent: moving from H1 directly to H3 skips a level and may make the hierarchy harder to follow. Review the content and structure rather than treating every skip as an automatic accessibility failure.

WCAG accessibility requirements

WCAG Success Criterion 1.3.1 (Info and Relationships) requires that information, structure, and relationships conveyed through presentation can also be determined programmatically or are available in text. Semantic heading elements can help expose page structure to assistive technology. This analyzer checks only a small set of heading patterns; its warnings and errors do not decide whether a page conforms to WCAG, ADA, Section 508, or another accessibility standard. A skipped level by itself is not necessarily a WCAG failure.

SEO impact of headings

Headings help describe a page’s sections, but this tool does not score keyword quality or predict search rankings. Use concise labels that accurately describe the section instead of repeating keywords. The length warning is deliberately soft: headings longer than 14 words or at least 70 characters may be worth editing, but a longer heading can still be the clearest choice for its content. Character counts include spaces in the normalized heading text; word counts split that text on whitespace.

The checker reports a missing H1 as a warning, repeated H1s and empty headings as errors, and skipped levels as warnings. It also reports a long-heading warning when either length threshold is reached. These checks are prompts for a human review, not a complete SEO audit or WCAG test. For example, a product guide with one H1, several H2 sections, and H3 subsections should show a readable outline; a jump from H1 to H3 points out a place to review the structure. Pasted page markup remains in your browser throughout the analysis.