Why I won’t install an accessibility overlay on your website

This is post 1 of 3 in the series “Don't Use Website Accessibility Overlays”

Anyone who knows me knows that I care a lot about making websites accessible. It’s a core part of the work I do. Whether it’s writing, design, development, or training, I’m always thinking about accessibility. So it may surprise you that I won’t install a tool claiming to make websites accessible. Let me explain why.

Let me start with some background for anyone less familiar with website accessibility.

What is web accessibility?

The goal of website accessibility is simple: make a website available to anyone on any device, centering the experience of people with disabilities. This means a website must work for someone regardless of their physical and cognitive abilities or the technology they use to operate and understand a computer.

Accessibility is one piece of an organization’s commitment to Diversity, Equity, and Inclusion (DEI). (Or DEIA if you add “A” for accessibility!). Adding a language translation function might not explicitly fall under technical accessibility, but it can definitely make a website more inclusive.

While doing this work, we can’t forget that each visitor is important, unique, and their own person. Someone’s physical and cognitive abilities are just one facet of their lived experience and chosen (or not) identity. (See also: Intersectionality.) Similarly, accessibility is only one consideration when working to build an inclusive website.

How is website accessibility assessed?

There are many considerations used to determine if a website is accessible. When determining whether a website is accessible, people tend to mean one of two things:

The WCAG standards are helpful for assessing a site and looking for potential issues.

  • Does a menu work when accessed with a keyboard rather than mouse?
  • Can a screen reader announce the number of items in a list?
  • Can a visitor pause a slideshow if it starts playing automatically?
  • Does a video have captions? Does a podcast have a transcript?
  • Does the website remain usable when zooming in to 200% or increasing the font size?

But it’s also important to remember that a technically compliant site could still suffer from serious usability problems that make it inaccessible in practice.

  • Can someone using a screen reader make a donation?
  • Can a person navigating by keyboard find and submit the contact form?
  • Can a person with color blindness understand a complex data visualization?

And remember that any time a website changes, a new piece of code, an image, or text could introduce a new accessibility issue.

What is an accessibility overlay?

So now we can talk about accessibility overlays, the tool I won’t install on your website.

Accessibility overlays are tools that go “on top” of a website and claim to partially or completely fix accessibility problems. Some tools modify the site’s code to allegedly meet WCAG standards. Other overlays provide “personalization” tools that supposedly help users customize the site to make it more usable. A list of prominent overlay products is available on the Overlay Fact Sheet website.

As documented on Overlay False Claims, many of these companies misleadingly imply or state outright that their tools make sites “compliant” with the Americans with Disabilities Act (ADA) or WCAG, “avoid lawsuits”, or even “show everyone you care”. (I suppose that last claim is debatable.)

Especially among nonprofits that care about inclusion and limited technology budgets, the promise of a quick fix and “showing they care” is hard to resist. Having seen a sales pitch from one overlay vendor, I know at least some of these companies specifically target networks of nonprofits and prey on their ideals of inclusion and lack of web accessibility knowledge.

Unfortunately, it is my strongly held personal belief that website accessibility overlays cannot do what they claim. (I use this language because some companies have shown a willingness to send cease & desist letters or file lawsuits against people who criticize them.)

Let’s get to the reasons why I won’t install these tools

Reason 1: Even if they worked, they don’t fix the underlying problem

Overlays that “fix” a site work by installing a special JavaScript file that heavily modifies the page for the visitor. Let’s examine that technique with a metaphor.

Imagine that you try to turn your car on one day and it is completely dead. You have it towed to the mechanic and they tell you that your engine has totally failed. But they have a quick and cheap fix. You’re thrilled! You don’t know how cars work, so this sounds great.

The next day, you go to pick up your car and there’s a new engine attached to the hood sitting above the old one!

A cut-out photo of an engine is crudely pasted on top of a car's hood with amusingly fake mouse-drawn duct tape affixing the engine to the car's hood. The car image behind the engine shows a gray 90s boxy Mitsubishi in a semi-open garage with a wet floor.
Car Image Credit: israfun on Flickr. CC BY 2.0
Engine Image Credit: Andrew Taylor on Flickr. CC BY 2.0

The mechanic did not fix the problem. Instead, they strapped on something new. Your car is now heavier and you probably can’t even see where you’re going because the engine blocks your view.

This is the philosophical approach of an accessibility overlay. If the underlying website is inaccessible, it does not make sense to add an additional layer of technology, code, and interface complexity to it, while leaving all the original problems unfixed.

And yet, that would still be somewhat defensible if overlays actually did fix all accessibility problems…

Reason 2: Overlays can’t possibly solve all your accessibility issues

The most optimistic claims from tools for testing website accessibility, say their tools find no more than 60% of all accessibility problems with automated testing. This is because many accessibility issues require human evaluation. Testing tools are often prone to false positive and false negative results.

When you think about it, this makes sense. Accessibility is fundamentally about communicating inclusively with humans. Humans and communication are complicated. Even in these days of AI fever dreams, no one is claiming they have technology that can think and communicate like a human.

As an example, take image alternative text. Depending on the contents of an image, its usage (e.g., is it in a link?), and the context of the surrounding page, the “correct” alternative text can vary wildly for a single image. Similarly, computers cannot evaluate with total accuracy whether a page’s heading outline makes sense and isn’t omitting important section headings or including inappropriate headings (all common heading mistakes).

Based on my knowledge of accessibility standards, my experience with the limitations of testing tools, and the vast numbers of people who share these concerns, claims that overlays can make a website totally accessible simply seem implausible.

Worse, they can sometimes break websites that were previously accessible:

The accessiBe overlay introduced code that was supposed to fix any original coding errors and add more accessible features. But it reformatted the page, and some widgets — such as the checkout and shopping cart buttons — were hidden from Mr. Perdue’s screen reader.

“For Blind Internet Users, the Fix Can Be Worse Than the Flaws” in the New York Times

Reason 3: People who rely on accessibility tools have better options [that work]

When selling accessibility “toolbars” (aka “widgets,” aka “overlays,” etc.) anyone without knowledge of assistive technology—the software and hardware some people with disabilities rely on—can be wowed by a demo. “Look at this shiny object! Your site visitors can use this tool on your site to turn on a special high-contrast mode, increase the font size, and read the page aloud!”

What they don’t say is that the people who rely on these functions to access the web already have tools for this and they can use them on any website. There are devices, apps, programs, and browser add-ons that empower users to customize any website in a consistent manner they can learn and adjust to their needs.

When you take a moment to think about it, relying on every single website on the internet to implement their own custom accessibility tools—each with slightly different designs and functions—doesn’t make much sense. Time for another metaphor.

Imagine that a plumber relied on every customer to provide their own tools for the repair. A few customers might have half the tools they need, but plenty would have none or just a single rusty wrench and a flathead screwdriver. Plumbers know what tools they need and they learn to use them. That way, when they encounter a new problem they have the tools of their choosing to meet their needs.

An old small toolbox is mostly filled by two beatup screwdrivers, a wooden-handled crank hand drill, and a medium-size wood-handled hammer. The toolbox is white with a tiny red grid of dots and red stripe filled with line drawings of simple wood objects like a birdhouse. A large red badge on the inside of the toolbox says "American Tool Chest".
Image Credit: el cajon yacht club on Flickr. CC BY 2.0

Accessibility standards help ensure that websites are coded in a way that allow visitors to customize the site appearance. To continue our plumbing metaphor, plumbers can rely on using their own tools because pipes, water heaters, faucets, and toilets all have fairly standardized components that a plumber can expect to encounter. Following standards allows people to anticipate and successfully use tools without tacking on additional supports.

This leads to an interesting overlap between Reason 1 (not addressing the underlying problem) and this 3rd reason (overlays are an inferior version of existing tools). Based on my experience with both types of tools, these accessibility customization toolbars often don’t work on website with underlying accessibility problems! For instance, the high contrast mode sometimes leaves text invisible or the font size option only changes the header and footer text size. “The overlay personalization farce” goes into incredible detail on the limitations of these tools.

The only way to make a website accessible is to ensure that the underlying code, images, and text are accessible. Adding tools on top of an inaccessible site can’t possibly be better than a website made to be accessible from the start. This makes sense as soon as you think about it.

I’ll end with a simple question: If these tools sold to website owners were so useful, wouldn’t it make more sense to sell them directly to people with disabilities so they could use them on any site? Why aren’t they?

Reason 4: Listen to the voices of those impacted most

Last, and most importantly, when we look at the real-world impact of these tools, they don’t appear to be making the web much more accessible. If anything, they may make it worse at times.

We know this by listening to the people affected. Remember: “People closest to the problem are closest to the solution, but furthest from power and resources.”

“I’ve not yet found a single [overlay] that makes my life better. I spend more time working around these overlays than I actually do navigating the website.”

Patrick Perdue in the New York Times

…I know with 100% certainty, any site which has deployed an overlay in the past year and a half has been less useable [sic] for both my wife and me—both blind.

GeauxEnder on Twitter via Overlay Fact Sheet

A new 2023 survey arising from the Reddit r/blind community (PowerPoint slide viewer) found 7 out of 10 users ranked their overlay experience as “Poor” (0 or 1 out 5). In WebAIM’s 2021 survey of accessibility practitioners, 7 out of 10 respondents rated “Overlay, Plugin, Widget Effectiveness” as “Not very effective” or “Not effective at all”.

The Overlay Fact Sheet documents even more testimonials about how these tools do not work and even make the web more difficult to use. Additionally, over 750 people “who are experts in this field & have dedicated their professional careers to the improvement of accessibility or are end users with disabilities (or both)” have signed the statement and committed to the following:

  1. We will never advocate, recommend, or integrate an overlay which deceptively markets itself as providing automated compliance with laws or standards.
  2. We will always advocate for the remediation of accessibility issues at the source of the original error.
  3. We will refuse to stay silent when overlay vendors use deception to market their products.
  4. More specifically, we hereby advocate for the removal of web accessibility overlay and encourage the site owners who’ve implemented these products to use more robust, independent, and permanent strategies to making their sites more accessible.

So this blog post and my upcoming presentation on this subject at the 2023 Nonprofit Technology Conference are among the ways I am aligning my actions with this commitment.

Warning! Misleading claims lead to inaction

When people accept the claims by overlay tool vendors and install them on the websites, they can believe they are “done” with accessibility. This is the worst possible outcome for a number of reasons:

  1. When treating accessibility as something to “fix” or “tack on” at the end, this ableist approach belittles the humanity of people with disabilities by not considering their needs as part of the collective from the start of a project (as the needs of able-bodied people always are considered).
  2. Accessibility is not something you can ever be “done” with. Making your website and organization inclusive, equitable, diverse, and accessible all require ongoing work and commitment.
  3. Even when overlays partially work (the best case scenario), the tools leave certain problems unfixed and paper over others that could break again if the tool changes or gets removed.

Accessibility overlays cannot make websites fully accessible. Installing one on your website sends the message that you did not consider the needs of all website visitors during your project. That is the opposite of inclusion.

But here’s the good news! If you take accessibility seriously and do the work to build your website with care and attention to the needs of people who use it, your website will be better for everyone.

So what do I do?

The second post in this series details what to do instead of using an accessibility overlay (i.e., how to make your website accessible!). If you’ve read this post, I suspect the answers won’t be too surprising. 😃


Honestly, there are more reasons not to use an accessibility overlay than I could include in a single post. So I encourage you to not just take my word for it but explore the experiences and arguments of other people as well. There is a preponderance of evidence supporting the claims in this article.

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