Free local tool

HTML Heading Structure Checker

Inspect H1-H6 order in pasted HTML locally and review empty headings, level jumps, and a textual outline.

Private by design: your input stays in this browser tab. This tool sends no input to a server and stores nothing after the page closes.

JavaScript is required for the interactive tool.

Method and limits

Parses up to 500,000 characters as inert source text. It does not render the HTML, load subresources, run scripts, compute the accessibility tree, or replace a full accessibility audit. Findings are conservative editorial checks rather than absolute conformance failures.