Deep Scan

Every Scheduled Scanning run checks each URL with two engines and shows the combined findings in one list. Deep Scan is the second of the two: rather than reading the page's markup, it drives the live page in a real browser and measures what a visitor actually experiences.

The standard engine (axe-core) reasons about the DOM and CSS: this element has no accessible name, this contrast ratio is 3.1:1, this ARIA attribute isn't allowed here. Deep Scan answers questions that only exist once the page is running — is the focus ring actually visible, does a sticky banner cover the control that just received focus, does pressing Escape close a dialog and return focus to where it was.

Deep Scan runs automatically as part of every scan on both Desktop and Mobile.

Where you see it

Issues table

On the URL Scan Details page, any issue Deep Scan found is marked with a Deep Scan badge and a violet highlight along the row, so those findings are visible while scanning the table rather than only after opening a row.

Expanding a Deep Scan row can show Evidence — screenshots that prove the defect, such as a focus ring captured with and without focus, or the overlay caught covering a control. The standard engine reasons about markup and never produces these images.

What it checks

Fourteen checks, covering:

• Focus – whether the focus ring is actually visible, whether a focused control is covered by something else on screen, whether the tab order matches what a sighted user would expect, and whether keyboard focus can ever get stuck
• Dialogs and tooltips – whether opening a dialog traps focus correctly and returns it to the trigger on close, and whether hover/focus-triggered content can be reached and dismissed with a keyboard
• Text and contrast – text readability over background images, text that gets clipped or overlaps when spacing is increased, and behavior under Windows High Contrast mode
• Layout – whether the page still works, without horizontal scrolling, at a narrow mobile width
• Live updates – whether dynamic content (toasts, status messages) is announced when it appears rather than being created already holding its message

A small number of checks — captions and flash/motion detection for video — are not yet available and are reported as not applicable rather than silently passing.

Things to know

• Scores include Deep Scan. A page's accessibility score reflects both engines' findings together.
• A check can appear more than once for the same issue if it found problems of different severity — for example, one instance of a naming issue that's serious and another that's minor.
• Findings aren't deduplicated against the standard engine. Where both engines can flag the same kind of problem — for example, a naming issue or a contrast issue — you may see it reported from both, with different evidence. The Deep Scan badge tells them apart.
• Deep Scan is careful about what it clicks. To surface issues in dialogs and dynamic content, it interacts with the page in a limited way, but it never activates anything that looks like it deletes, removes, signs out, unsubscribes, pays, checks out, places an order, publishes, or archives.