What automated scans can and cannot find

Automated scanning is fast, repeatable and good at catching a specific kind of problem. It is not a full accessibility test, and it cannot tell you that a site is accessible. This page explains the difference so you can use your results with the right expectations.

What a scan is good at

A scan reads the code of each page and checks rules that a computer can decide. For example:

• Text that does not have enough contrast against its background.
• Images with no text alternative at all.
• Form fields with no label, and buttons or links with no accessible name.
• A missing page language or page title.
• Invalid or misused ARIA attributes, and broken heading or landmark structure.

These checks are worth running often. A site changes every time someone publishes a page, edits a template or adds a plugin, and a scheduled scan will catch problems that appear later.

What a scan cannot decide

Many requirements depend on meaning and context, which a computer cannot judge:

• Whether alt text is accurate. A scan sees that alt text exists, not whether it describes the picture.
• Whether you can use every feature with a keyboard alone, and whether focus moves in a sensible order.
• How the page sounds with a screen reader, including whether the reading order makes sense.
• Whether captions and transcripts are correct, and whether audio description is present where needed.
• Whether instructions, error messages and labels are clear and easy to understand.
• Whether content still works when zoomed to 200 percent or viewed on a small screen.
• Anything behind a login or inside a form flow, since the scanner reads public pages and does not sign in or submit forms.

Issues and suggestions

Results are split in two. Issues are failures of a WCAG success criterion. Suggestions are best-practice items that are not strict conformance failures but still help people who use assistive technology. Fix issues first. Treat suggestions as a second pass.

A manual pass you can do in an hour

Run through these on your most important pages, such as the home page, a form and your checkout or contact flow:

1. Keyboard only. Put the mouse aside and use Tab, Shift+Tab, Enter and Space. Can you reach and use everything? Can you always see where focus is?
2. Zoom. Zoom the browser to 200 percent. Is anything cut off or overlapping?
3. Screen reader. Try VoiceOver on a Mac or iPhone, NVDA on Windows, or TalkBack on Android. Listen to the page from the top.
4. Forms. Submit a form with mistakes. Is each error described in words and linked to the right field?
5. Motion and media. Check that videos have captions and that nothing flashes or moves without a way to pause it.

Two free tools can help while you work: the contrast checker and the ARIA inspector. Neither needs an account.

What this means for what you say publicly

Do not describe your site as "WCAG compliant" or "fully accessible" based on a scan alone. Our accessibility statement generator follows the same rule. It says "partially conformant" when there are known issues, and when there are none it says only that automated testing found no issues, with a note that full conformance needs manual testing. See accessibility statements.