Overview
An overlay is a JavaScript widget that promises to make your site accessible and compliant by patching pages in the browser. This page explains, technically and without drama, why that promise cannot be kept, and why regulators, courts, and the accessibility community have all said so.
If you are comparing an overlay against an audit for your budget, the head-to-head is in manual audit vs automated widgets.
How an overlay works
- You paste a script tag into your store.
- On each page load, the script scans the rendered page.
- It applies automated patches, like guessed alt text and injected labels, and renders a settings panel for font size and contrast modes.
- Your actual store code never changes. Remove the script, and every patch disappears with it.
Understanding step 4 is enough to understand the whole problem. The overlay is a costume, not a repair.
Why this cannot reach compliance
The detection ceiling. A machine can only fix what a machine can detect. Automated checks catch roughly a third of WCAG failures, as measured in why automated tools miss most issues. The overlay’s repair ceiling is even lower than its detection ceiling, because detecting a problem is easier than fixing it correctly without context.
The judgment problem. The highest-risk failures need human judgment. No script can know your product photo shows a blue ceramic mug with a cork lid rather than “image.” No script can decide the logical focus order of your custom checkout. No script can restructure a heading hierarchy that misleads screen reader users about how your page is organized.
The interference problem. Screen reader users arrive with their own configured tools. An overlay that intercepts keyboard events or rewrites the page can actively conflict with them. This is the core complaint in the Overlay Fact Sheet, signed by hundreds of accessibility practitioners, many of them disabled users themselves. Some maintain browser extensions specifically to strip overlays from pages before using them.
The record
- FTC, January 2025: accessiBe ordered to pay $1 million for misrepresenting that its product made sites WCAG compliant, and for undisclosed paid reviews.
- Litigation data: UsableNet has tracked hundreds of ADA suits per year against sites with overlays installed. Plaintiffs’ firms screenshot the site failing with the widget active. Some complaints name the overlay as an additional barrier.
- Community consensus: the Overlay Fact Sheet recommends against overlays as a compliance strategy. No major accessibility organization endorses them.
What to do instead
The unglamorous path that works: find the real issues, fix them in your actual store, document it.
- Run the 10-minute self-check to find the loud problems.
- Fix the common failures. Most are small, and the fixes stay fixed.
- Get a manual audit for the issues machines and self-checks miss, and keep the dated report.
Example
A store installs an overlay in January. In June, a plaintiff’s screen reader still cannot name the add-to-cart button, because the underlying markup never changed and the overlay guessed wrong. The complaint includes screenshots taken with the widget active and running. The monthly fees bought nothing that mattered in the one moment the store needed protection.
Common mistake
Reasoning that “some accessibility improvement” justifies the overlay while real fixes wait. In practice the overlay postpones the fixes indefinitely, annoys the users it claims to serve, and marks your store for the firms that track overlay deployments. Partial cosmetic coverage is not a step toward compliance. It is a detour away from it.