See the headings like a screenreader!

Visit the h123 homepage and drag the Show Headings link to your bookmark bar.

Download the latest extension from Releases:

• Chrome / Edge / Brave — h123-chrome.zip
• Firefox — h123-firefox.zip
• Safari — convert the Chrome ZIP using Apple's safari-web-extension-converter

Screenreaders navigate pages by heading hierarchy (h1 → h2 → h3 …). When heading levels are skipped, the page becomes hard to navigate for blind users.

h123 shows you the heading structure of any page exactly as a screenreader sees it:

• Only visible headings are shown (not display:none, not aria-hidden)
• Skipped heading levels are flagged in red
• Shadow DOM boundaries are traversed
• Visually-hidden headings can be highlighted

yarn install
yarn build

yarn build compiles the bookmarklet, packages the browser extensions, and generates the GitHub Pages site into docs/.

Build outputs (all in dist/):

• Push to main / master — builds and deploys the GitHub Pages site.
• Push a tag v* — builds and creates a GitHub Release with the extension ZIPs attached.

Hinderling Volkart AG