Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
Heading Structure Checker
Validate HTML heading hierarchy for SEO and accessibility.
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- Heading Structure Checker
Summary
Issues
Structure Outline
What is a Good Heading Structure?
A proper heading structure (<h1> through <h6>) creates a logical outline for your content. It helps search engines understand your page hierarchy and improves accessibility for screen reader users. Best practices include using one <h1> per page, not skipping heading levels, and using descriptive text.
How to Use
- Paste HTML — Enter HTML content containing heading tags.
- Check — Click Check Structure to analyze the heading hierarchy.
- Review issues — Errors (multiple h1, missing h1) and warnings (skipped levels) are highlighted.
- View outline — A visual tree shows the heading structure with indentation per level.
Frequently Asked Questions
How many h1 tags should a page have?
Exactly one. The <h1> tag represents the main topic of the page. Multiple <h1> tags confuse search engines and screen readers.
Can I skip heading levels (e.g. h1 to h3)?
No. Skipping heading levels creates a gap in the document outline. Always maintain a logical hierarchy (h1, h2, h3...) without skipping levels.
Is my HTML sent to a server?
No. All analysis happens in your browser using the DOM parser. Your content never leaves your device.
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