Accessibility & Contrast Checker — support
It says the page is blocked
Browser pages — the new tab page, settings, the extension store itself — cannot be read by any extension. Open a normal web page and click again.
It found nothing, but I know the page has problems
Automated checks cannot find every accessibility problem. It cannot tell you whether alt text is accurate, whether a heading order makes sense to a reader, or whether a form is usable by keyboard. "No violations" means the automated rules passed, not that the page is accessible. The "needs a human to check" list is where the tool tells you what it could not decide.
It says some embedded documents were not checked
Content embedded from another page — an iframe, a frame, or an object or embed holding a document — is not read. The extension checks the page you are on. When a page has any, it tells you how many it skipped, in the popup and in any exported report, so that a page whose content all lives inside one does not come back looking clean when nothing in it was examined. The count reaches inside open web components (shadow DOM) as well as the page itself.
To check an embedded page, open it in its own tab and run the check there.
Every exported file says this, including the CSV. The CSV opens with a short scope block — the page, when it was scanned, how many elements failed, how many embedded documents were not checked, and how many items need a human — above the table of failing elements. A page with nothing wrong in the part that was checked therefore still exports a file that says so, rather than an empty table that could be mistaken for a clean result.
It says a closed component was not checked
Some pages build parts of themselves as components whose insides are sealed off from scripts — a closed shadow root. The accessibility rules cannot read inside one, so nothing in there is checked. This extension can still SEE that such a component is present, and counts it, so the popup and every export tell you how many there were. Nothing inside them is counted as a problem and nothing inside them is cleared.
A correction, 28 September 2026. Until today this page and the store listing said a closed shadow root was "unreachable by any script" and that no extension could reach one. That was wrong. Chrome has given extensions chrome.dom.openOrClosedShadowRoot since Chrome 88, and an independent reviewer disproved the claim by using it. The claim is withdrawn and the extension now uses that API to count what it cannot check. It still does not scan inside closed components — but it no longer pretends that is impossible rather than unbuilt.
Can a page fake its own result?
No. The rules run in an isolated copy of axe-core that the extension injects; a page's own scripts cannot see it, replace it or answer for it. A page that ships its own axe, including one written to report no problems at all, is ignored and the real scan runs anyway. This is checked against a real page carrying a fake axe every time the test suite runs.
Which rules does it run?
axe-core's standard WCAG 2.0, 2.1 and 2.2 A and AA rules — 63 rules in axe 4.13. axe also carries a handful of WCAG-tagged rules it marks experimental or deprecated and switches off by default (for example "p-as-heading" and "td-has-header"); this extension leaves those off too, because they produce false alarms. AAA rules are not run. An option in the popup adds axe's 30 best-practice rules, which are not WCAG requirements.
The contrast ratio is different from another checker
Two common reasons:
- Rounding. Some tools round down (2.849 becomes 2.84), this one rounds to the nearest (2.85), the same way the WebAIM checker does.
- Background. Text over an image, a gradient, or a semi-transparent layer has no single background colour. axe reports those as "needs review" rather than guessing, and this extension does the same.
"Show on page" says it could not find the element
The page changed after the scan — a menu closed, a list re-rendered, a single-page app moved on. Click Rescan and try again.
Is it really free?
Yes. Every feature — the scan, every element, the colour suggestions, the whole-page outline, export to CSV, HTML or JSON, and the best-practice option — is free. There is no payment, no licence key and no account, and the extension makes no network requests.