Accessibility Overlay

An accessibility overlay is a product, usually a single line of JavaScript added to a site, that promises to detect and automatically remediate accessibility problems at runtime, often paired with a widget that lets visitors adjust things like text size, contrast, or spacing. Overlays are marketed as a fast, low-effort route to compliance, which is a large part of why they are controversial.

The core problem is the same limit that applies to all automated tooling: only a minority of WCAG issues can be detected and corrected by software without human judgment. An overlay cannot reliably write accurate alternative text, fix an illogical reading order, make a custom component genuinely operable by a screen reader, or repair a broken keyboard flow. Claims that a script can make any site fully compliant or lawsuit-proof are not supported by how accessibility testing actually works.

There are also documented downsides specific to overlays. They can interfere with the assistive technologies that disabled users already run, and many people with disabilities and accessibility practitioners have publicly opposed them. A widely cited industry effort, the Overlay Fact Sheet, was signed by hundreds of accessibility professionals and users cautioning against relying on overlay products, and overlays have themselves been named in accessibility lawsuits rather than preventing them.

The durable alternative is to fix accessibility in the source: remediate the underlying HTML, ARIA, and content so the experience is genuinely accessible, and verify with automated scanning plus manual and assistive-technology testing. Diagnostic scanning that tells you what to fix is fundamentally different from an overlay that claims to fix it for you; the former informs real remediation, the latter substitutes a claim for the work.