Tab trail

1. 1Drag the Tab trail button to your bookmarks bar. It turns into a bookmark you can click on any site. Don't see the bookmarks bar? Press Ctrl+Shift+B, or Cmd+Shift+B on a Mac. In Firefox, use the console instead (see below).
2. 2Open your site and click the bookmark.
3. 3Press Tab and follow the numbers, or press Play and it walks every stop for you. Click the bookmark again or press Escape to close it.
4. 4Your bookmark keeps the version you dragged. To get new checks, delete it and drag the button again.

• A green 0 means that check found nothing. A red number means it found something, and the chips under it take you there.
• In the Log, OK passed, PROBLEM needs a fix, SKIPPED was not judged and says why, and INFO is a note.
• Out of order is judged only for the Tab presses you make. Press Tab to the end, then Shift+Tab back.
• Hidden focus is judged once the page stops scrolling. Press Play to test every stop.
• Lost focus is judged only for the popups you open and close.
• Everything is tested at your window size. Try a narrow window too.

Copy for AI copies only the problems, each with its WCAG rule, what should happen, a CSS selector, the HTML, the component that drew it, a fix hint and how to check the fix. Paste it into your coding AI and it knows where to look.

While Tab trail is open, the page has window.__tabTrail, so a test or an AI agent can run it with no clicks:

await window.__tabTrail.play()
window.__tabTrail.report()
window.__tabTrail.log()
window.__tabTrail.state()
window.__tabTrail.version
window.__tabTrail.close()

In a Playwright test, it fails with the whole report when Tab skips something:

import { test, expect } from "@playwright/test";

test("Tab reaches everything", async ({ page }) => {
  test.setTimeout(120_000);
  const script = await (await fetch("https://matjazkorosec.com/tools/tab-trail.js")).text();
  await page.goto("http://localhost:5173/");
  await page.addScriptTag({ content: script });
  const report = await page.evaluate(() => window.__tabTrail.play());
  const log = await page.evaluate(() => window.__tabTrail.log());
  expect(log.filter((l) => l.result === "PROBLEM" && !l.fixed), report).toEqual([]);
});

Nothing happens when I click the bookmark?

Some sites block scripts from bookmarks. Open the script (under "What's in the code"), copy all of it, and paste it into the browser console on that site.

Tab skips every link on a Mac?

Safari and Firefox do that until you turn it on. Safari: Settings, Advanced, "Press Tab to highlight each item". Firefox: System Settings, Keyboard, "Keyboard navigation".

Escape doesn't close it?

While a popup on the page is open, Escape closes the popup first, and during Play it pauses. Press Escape again, or click the bookmark.

Open in new tab does nothing?

Your browser blocked the pop-up. Allow pop-ups for that site and press it again.

No red on a menu that opens on hover?

If its CSS comes from another site, the browser lets no script read it. The Log lists that style sheet as SKIPPED.

Using Firefox?

Firefox can't save it as a bookmark: a bookmark there can be at most 65,536 characters long, and Tab trail is 159,041. Open the script (under "What's in the code"), copy all of it, press F12 on your site, open Console and paste it. If Firefox asks, type allow pasting first.

On a phone?

It needs a keyboard and a desktop browser. Press the button here to watch Play walk this page.

• Tab trail is 1 script of plain JavaScript, 2139 lines. All of it is in the file below.
• It reads the page you have open: what the Tab key can reach, and what looks clickable.
• It draws in 1 layer it adds to the page, so the site's styles can't touch it. Closing it removes the layer.
• It changes nothing else on the site. It only moves focus and scrolls, the way your Tab key would, so the site's own focus code runs as usual. Play never clicks.
• It sends and loads nothing: no network requests, no cookies, no local storage.
• While it is open it adds window.__tabTrail for scripts. If you open the Log in a new tab, it names your tab so it can switch back, and clears the name when you close it.
• The links in its panel and Log all go to this page.

Open the script

Tab trail is free under the MIT License. Use it, change it and share it, at work too, as long as every copy keeps the notice at the top of the script: "Copyright (c) 2026 Matjaž Korošec".

Found a bug? Press Copy log and email it to me.

Next to the tools you know

• axe and Lighthouse read the code. They never press Tab.
• Accessibility Insights numbers your Tab stops in Chrome and Edge. Tab trail does that in any desktop browser, with no extension.
• Tab trail also reads your CSS for menus that open only for the mouse, and catches focus hidden under a sticky bar or lost when a popup closes.
• Use them together. Tab trail is the keyboard part.

What it leaves to a full audit

• It spots clickable things by the pointer cursor, links with no address, button roles and click handlers in the HTML. A click handler added only by script, with no pointer cursor, stays hidden.
• It doesn't check if the focus ring is visible or has enough contrast, or what a screen reader says. Spotlight helps you look for yourself. Pages inside frames are skipped.
• Style sheets loaded from other sites can't be read, so hover menus styled there are not checked.
• It's made for Chrome, Edge, Firefox and Safari on a desktop computer. On a Mac, turn on Tab for links first, and Firefox needs the console (see above).