Heading Hierarchy & Outline Visualizer
Skipped heading levels (H1 → H3), multiple H1s, and empty headings confuse both search engines and screen readers. Paste your HTML and instantly see the document outline as a visual tree with every structural issue flagged.
Tool interface
Document Outline
Top Heading Keywords
Clean Outline (Text)
Introduction
Heading tags create the semantic skeleton of your content. When that skeleton is broken — skipped levels, missing H1s, empty tags — search engines struggle to understand your page hierarchy and screen-reader users lose their navigation map. This tool makes the invisible structure visible.
How It Works
- HTML is parsed with
DOMParserand allh1–h6elements are extracted in DOM order. - Each heading is rendered as an indented tree node with its level badge.
- Structural rules are checked: single H1, no level skips, no empty text.
- Word frequency across all headings is computed to flag keyword repetition.
Privacy
Your HTML is parsed entirely in your browser using DOMParser. No content is transmitted anywhere. No API calls, no tracking.
Limitations
- Cannot detect headings injected by JavaScript after page load (paste the final rendered HTML).
- Does not evaluate heading text quality or relevance — only structure.
- Keyword frequency is a simple word count, not semantic analysis.
FAQ
Is it OK to have multiple H1 tags?
While HTML5 technically allows multiple H1s in sectioning elements, best practice for SEO and accessibility is one H1 per page. Google's John Mueller has confirmed multiple H1s don't cause a penalty, but a single H1 is cleaner.
Does skipping heading levels hurt SEO?
It's primarily an accessibility issue (WCAG 1.3.1), but it also makes it harder for search engines to understand your content hierarchy. Fix skips for both reasons.
Is my HTML uploaded?
No. Everything is parsed locally in your browser. Nothing is transmitted.