Free Header Structure Checker

How this tool computes its result

Parses pasted HTML via DOMParser, extracts all H1-H6 tags in order of appearance, and measures header quality against 100-point scale. Scoring deducts points for missing or multiple H1 tags (30 points), missing H2 when multiple headers exist (15 points), hierarchy violations where a level jumps more than one tier without intervening headers (15 points), empty headers (10 points), and headers exceeding 70 characters (5 points). Hierarchy is checked by tracking previousLevel and flagging jumps like H1 -> H3. Final score is clamped to 0-100 and mapped to a letter grade: A for >=90, B for >=75, C for >=60, D for >=40, else F.

Worked example

Pasting an HTML document with one H1 ("Main Title", 11 chars), three H2s ("Section A", "Section B", "Section C" between 9-11 chars), and no H3-H6 tags: all headers are valid hierarchy, none exceed 70 chars, so no deductions apply beyond the flat structure check. No H3 tags under H2s triggers a recommendation ("Consider using H3 tags to create subsections") but no point deduction since the hierarchy itself is valid (H1 -> H2 -> H2 is acceptable). Score remains 100, grade A.

When not to use this tool

This checks only header structure and character length - it does not validate whether header text is unique, semantically meaningful, or keyword-optimized for SEO; it does not measure readability or grade the prose quality of your headings, only their DOM structure.

Common mistakes

• - Pasting a full HTML document including DOCTYPE and scripts when only the content section is needed - the parser still works but counts all headers site-wide, which may inflate header counts if you're trying to assess a single section in isolation.
• - Assuming the "over 70 characters" warning is a hard SEO rule - the tool flags headers >70 chars as potentially hard-to-scan for readability, but SERP snippets and screen readers handle longer headers fine; this is a style guideline, not a requirement.
• - Expecting the tool to flag improper heading hierarchy as an issue when you skip from H1 to H3 in the structure - it does flag such jumps as "Header hierarchy issues detected," but the score penalty is modest (-15 points) and won't tank a grade if other signals are solid.

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