Accessibility overlays are a billion-dollar industry selling a product that does not work.
The pitch is simple. Paste a line of JavaScript on your site. The overlay runs in the browser, detects disabled users by heuristic, and "optimizes" the page for them. Screen reader users get one thing, low-vision users another, motor-disabled users another. The vendor issues a compliance statement. You are now "accessible."
Every claim in that pitch is wrong in a specific way.
What the overlay actually does
The overlay is a JavaScript layer that injects ARIA attributes into the DOM, applies CSS filters for contrast, toggles reduced-motion classes, and sometimes provides a menu of "accessibility settings."
On a real page with a real screen reader:
- The injected ARIA frequently conflicts with the site's existing markup. Screen readers read the wrong thing, or the same thing twice, or silently misstep.
- The "detection" of disabled users is naive. It guesses based on user agent, cursor patterns, or a default toggle. It is wrong a lot.
- The overlay menu itself is often less accessible than the site it is "fixing." The irony is audit-able.
- Dynamic content on the actual site fights with the overlay's injected state. Forms break. Modals break. Navigation breaks.
Sites I have audited that ship overlays consistently score worse on real screen reader tests than the same sites without them.
Who this harms
Disabled users.
Not a theoretical disabled user. The ones actually visiting the site. They arrive, the page is inaccessible in the usual ways, the overlay adds new failures on top, and the overlay has now broken the workarounds they had developed for sites like this.
The National Federation of the Blind stated its position explicitly in 2021: overlays are harmful. They are not alone. Blind users have been documenting overlay failures publicly since around 2020. Entire community-maintained lists exist of overlays that have broken specific assistive-tech combinations.
The industry response has been marketing. None of the major vendors have retracted the "makes your site accessible" claim. Some added disclaimers in legal fine print. The product did not change.
Why the industry exists anyway
Because it is selling the wrong thing to the wrong customer.
The overlay is not sold to accessibility engineers. It is sold to legal departments worried about the Americans with Disabilities Act and similar laws in Europe. The pitch to legal is: here is a shield against lawsuits. The product does not need to work for disabled users. It needs to produce a compliance statement for the attorney.
This is why overlays have kept growing despite every practitioner recommendation against them. The engineering validity of the product and its commercial validity are unrelated.
What this tells you about accessibility-as-product
Any vendor that promises accessibility as a drop-in plugin is selling the same thing. The specific technology varies: overlay, AI-generated alt text, "accessible widget library." The shape is the same. Accessibility treated as a checkbox, bought rather than built.
Real accessibility is not a product. It is a property of a site, built from decisions at every layer, audited by people who understand assistive tech. You cannot paste it in.
When someone pitches a single-line-of-code accessibility solution, what they are actually pitching is a reduction in your legal exposure in exchange for a fee, with the harm to disabled users as an externality they are not quoting.
The position
The overlay industry is a rare case where the professional consensus, the user community, and the empirical evidence all point the same way, and the product keeps selling anyway.
If you are considering an overlay: don't. The money goes into making your site less accessible, not more.
If you have one installed: remove it. The path to compliance without harm goes through actual accessibility engineering. There is no shortcut, and the shortcut causes damage.