Developer tools

Heading Outline Checker

Check pasted HTML for heading hierarchy issues.

Runs locally in your browser — nothing is uploaded.

About this tool

Use Heading Outline Checker to complete this focused task without sending your content to a third-party service.

Paste or enter your content, run the tool, and review the result before using it.

Check the labels, units, and input format before running the tool.
Review the result, then use the copy button where available.
For important decisions, verify your inputs with an appropriate professional source.

Is my information private?

Yes. This developer tools processes your input in the browser and does not upload it.

Is this tool free?

Yes. You can use it without creating an account.

Use Heading Outline Checker locally to inspect a focused accessibility aspect of pasted HTML.

Does this tool send my data anywhere?

No. Its calculation or transformation happens on your device.