Heading Structure Analyzer

Is your heading outline logical, or just styled to look that way?

Designers often choose heading tags for their font size, which leaves pages with an H4 under an H2, or no H1 at all. Sighted visitors rarely notice, but screen readers and crawlers work from the tags, not the styling. This analyzer reads the tags from pasted HTML and lays them out as a nested tree with level badges, so the real hierarchy is obvious. It runs in the page itself and does not contact your site.

Step by step

1. Open the page you want to review and copy its HTML. Right click and view source for the server version, or use Inspect, select the html element and copy its outer HTML to include anything JavaScript added.
2. Paste that into the large text box.
3. Press "Analyze Headings". The outline appears with H1 to H6 badges, indented by depth.
4. Check the red issues panel, or the green confirmation if nothing was found, and the count per level at the bottom.

What to watch for

The tool looks for three problems only. It reports a page with no H1, a page with two or more H1s, and any place where depth increases by two levels or more (H1 straight to H3, for example), quoting the first 30 characters of the heading where the jump happens. Going from deep to shallow is fine and passes. Indentation, line breaks and attributes inside a heading tag do not get in its way, since the text is collapsed onto a single line. What it cannot see: headings written in Markdown, and headings a page builds with JavaScript unless you paste the rendered DOM. When the outline looks shorter than the page, suspect one of these first.

Questions people ask

Is having two H1 tags bad for SEO?

Google has said publicly that several H1s do not cause a problem for Search, and HTML permits them. The tool still flags it because one H1 that names the page topic is the clearest pattern for readers and assistive technology.

Why do skipped levels matter if the page looks fine?

People using screen readers often jump between headings to find their way around. A jump from H2 to H4 suggests a missing section, which is why accessibility guidance recommends keeping ranks in order.

Can I paste a URL instead of HTML?

No. The box expects page source. A bare URL contains no heading tags, so you will get the "No headings found" message.

Further reading: H1 Only in Rendered HTML and Empty Headings: How to Fix Them.

The same tool is also published on the static mirror at seoprocheck.github.io, and the rest of the set is on the free tools page.