Heading Structure Checker

What this tool does

Inspect H1–H6 tags in a pasted HTML string. A regular expression extracts one-line heading tags, removes nested tag strings and reports levels/text. Warnings cover missing/multiple H1, skipped levels, empty headings and more than 50 headings.

How to use Heading Structure Checker

Prepare the input. Paste the relevant HTML.
Run or configure the tool. Read the extracted heading list and level counts.
Check and use the output. Investigate warnings in the real page instead of mechanically renumbering headings.

How this tool works

A regular expression extracts one-line heading tags, removes nested tag strings and reports levels/text. Warnings cover missing/multiple H1, skipped levels, empty headings and more than 50 headings.

Worked example

Input: <h1>Main</h1><h3>Detail</h3>

Output: H1 Main and H3 Detail; warning: skipped level H1 → H3.

Limits, assumptions and interpretation

The regex is not a full DOM/accessibility-tree parser; multiline heading contents and generated markup can be missed.

An H1 count or level warning is a review signal, not a complete accessibility or SEO rule.
Entity decoding and screen-reader relationships are not tested. Review the actual page structure with proper accessibility tools.

Supported inputs and limits

<h1>Main</h1><h3>Detail</h3>
The regex is not a full DOM/accessibility-tree parser; multiline heading contents and generated markup can be missed.
An H1 count or level warning is a review signal, not a complete accessibility or SEO rule.
Entity decoding and screen-reader relationships are not tested. Review the actual page structure with proper accessibility tools.

Frequently asked questions

What does this tool actually do?

A regular expression extracts one-line heading tags, removes nested tag strings and reports levels/text. Warnings cover missing/multiple H1, skipped levels, empty headings and more than 50 headings.

What should I check before using the result?

The regex is not a full DOM/accessibility-tree parser; multiline heading contents and generated markup can be missed. An H1 count or level warning is a review signal, not a complete accessibility or SEO rule. Entity decoding and screen-reader relationships are not tested. Review the actual page structure with proper accessibility tools.

Is information sent to a server?

Tool inputs are processed in this browser. This product does not use analytics or send your input to an external API. Clicking an external website link still visits that website.