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Paste HTML source code and instantly validate your heading hierarchy for SEO and accessibility. Find missing H1s, skipped levels, empty headings, and more.
Check your HTML heading structure in seconds. This free heading validator extracts every H1 through H6 tag from your source code, maps the hierarchy as a visual outline, and flags SEO and accessibility issues. No signup, no data stored. Everything runs in your browser.
Search engines use heading tags (H1-H6) to understand the structure and topic hierarchy of your page. A clear heading structure helps Google identify your main topic (H1), subtopics (H2), and supporting points (H3-H6). Pages with proper heading hierarchy tend to rank better because search engines can parse the content more accurately. A missing or duplicate H1 confuses crawlers about your page's primary topic.
WCAG 2.1 Success Criterion 1.3.1 (Info and Relationships) requires that heading levels convey the document's logical structure. Screen readers let users navigate by headings, so skipping levels (for example, jumping from H1 to H3) breaks that navigation. Every page should have exactly one H1, and heading levels should not skip. H2 follows H1, H3 follows H2, and so on. Empty headings are also a violation because they create dead-end navigation points for assistive technology users.
The most common mistakes are: (1) Missing H1 tag entirely. Every page needs exactly one. (2) Multiple H1 tags, which confuses search engines about the primary topic. (3) Skipping heading levels, like jumping from H2 to H4 without an H3 in between. (4) Using headings for visual styling instead of document structure. (5) Empty heading tags that contain no text. (6) Extremely long headings over 100 characters that dilute keyword focus and are hard for users to scan.