Heading Structure Checker
Check HTML heading hierarchy online: H1-H6 outline, skipped heading levels, duplicate H1, and empty headings.
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What is Heading Structure Checker?
A heading structure checker parses pasted HTML and builds a visual outline of every H1-H6 heading in the document. It flags skipped heading levels, duplicate H1 tags, empty headings, and pages without a single H1. Because headings form the backbone of how screen reader users and search engines navigate a page, keeping the hierarchy clean is a core part of web accessibility and on-page SEO. This free tool runs entirely in your browser — paste any HTML and get an instant structure report with line-level detail.
Key Benefits
- Renders an indented visual outline of the entire heading hierarchy at a glance
- Catches skipped heading levels that confuse screen reader navigation
- Enforces exactly one H1 per page for clearer SEO and accessibility
- Flags empty headings and heading text issues before they ship
- Works fully offline in the browser with no account or upload
Common Use Cases
- •Auditing existing pages during an accessibility or WCAG review
- •Checking templates and components before they are deployed
- •Reviewing CMS-authored content where editors control heading levels
- •Verifying SEO on-page structure for blog posts and landing pages
- •Teaching heading hierarchy best practices to content and dev teams
How to Use the Heading Structure Checker
- Paste your HTML: Copy the HTML markup of a page — a full document or just a fragment — and paste it into the text area. Or click Load Sample to try the tool with example markup.
- Review the outline: The tool renders an indented outline of every heading with its level, text, and line position. Skim it to see the document structure at a glance.
- Check the findings: Read the issue list for skipped heading levels, multiple H1 headings, empty headings, or a missing H1. Each finding shows the line and column to fix.
- Copy or download the report: Export the outline and findings as a text report with one click, or download it as a file to share with your team or attach to an issue.
Key Features
- Parses all H1-H6 tags with exact line and column positions
- Renders an indented visual outline of the full heading hierarchy
- Detects skipped heading levels, multiple H1, and missing H1
- Flags empty headings that provide no content to users
- Summary cards for heading count, errors, warnings, and H1 count
- Copy or download a plain-text report with the outline and findings
Frequently Asked Questions
What is a heading hierarchy and why does it matter?
A heading hierarchy is the order of H1-H6 tags in a document, from the page title down to sub-sections. Screen reader users navigate pages by jumping between headings, and search engines use them to understand structure. A logical hierarchy with no skipped levels makes content easier to scan and more accessible.
How many H1 tags should a page have?
Best practice is exactly one H1 per page, typically the page title or main heading. Multiple H1 tags dilute the document structure and can confuse both assistive technology users and search engines about the primary topic.
What does a skipped heading level mean?
A skipped level happens when a heading jumps down more than one level, such as going from an H2 straight to an H4. It usually means a heading was deleted or a section was restructured. Skipped levels break the logical outline that screen reader users rely on to navigate.
Is my HTML uploaded anywhere?
No. The tool parses and analyzes everything locally in your browser using JavaScript. Nothing is sent to a server, so you can safely check internal, draft, or confidential pages.