Post source? Still overlays!

first published: July 23, 2026 and collected in: accessibility

On Monday, I learned of a new way overlay companies are trying to sell their wares and take people's money. You may know of “Accessibility Overlays” (if not, please read the Overlay Fact sheet). Overlays pretend to remedy inaccessible websites by transforming the HTML to something accessible. This usually only sort of works if the site is already accessible, and usually makes things worse, not better.

Since the term “Overlay” is somewhat burned, two new ways of talking about it have been termed:

1. Edge Computing (which may not be coined by Overlay vendors, but is used by them, see below).
2. Post-Source Code and Content.

Some Overlay Providers (Level Access, AudioEye) have founded the “Accessibility at the Edge Community Group”. This is a community group in the W3C.

Great, you might think, the W3C does condone Overlays. That is false. Anyone can found a community group and run it. It has to follow rules, but they do not make specs or influence spec creation (though they try at TPAC.

I won't judge the Community Group here, but I am a member of one myself and therefore have an idea how much or how little they can influence.

My problem is though, that this group has produced a report in which they argue that most websites are a mix of cross source content (original stuff, ads, videos, social ads, and more ads) and that, because of this, only “post source remediation” can provide an accessible experience.

This is problematic in so far that it gives them the veneer of having produced an official note. Look at it. It looks like it could have come from a working group. Besides, their premise is only true for highly commercialised websites. Realistically the web is still full of smaller sites (and it seems crafting is growing again) and AI slob (where all hope is dead anyway).

Next, post source means once rendered and inside the browser. For this, web masters (yes, this is a bit sarcastic) should (this is not in the report, but implied) turn to overlay or other tool provider, since it would be too much work to do it correctly in the first place.

Having worked in the Ad Tech industry before, their thinking won't find friends there: “Those that impair accessibility are rejected and replaced by another candidate advertisement until one is obtained which does not impair accessibility. It is that WCAG conformance content that is then actually displayed to the user.” (Quote source)

When I was in Outbrain, we actively worked on making our widgets accessible. And this is the key: Instead of helping companies to create accessible experiences from the start (by auditing, automating, supporting and teaching), which brings accessible experiences to the masses, they want to sell useless overlays or “on the fly” code changing tools which do not work, since accessibility can still only be automated to up to 40%.

So. If you hear: “Post Source Code”, “Post Source Enhancement” or “Post Source Accessibility”, please remember: It’s just overlays. “Edge Computing” is just overlays. Overlays do not work!

And just because you see ”W3C” somewhere, do not believe it is official. Check and protect ya neck!