Accessibility Overlays
Accessibility overlays are automated tools that claim to find and fix accessibility issues on websites.
What’s in it
What is it for?
Accessibility overlays are automated tools that claim to find and fix accessibility issues on websites. They work by modifying a website with a bit of JavaScript, and usually have an associated toolbar, app, or widget. The aim is that businesses won't have to work on the accessibility of their site, and instead can simply add a pre-built overlay to fix things for them. They can detect some basic issues, such as colour contrast and text size (which isn't enough for a fully accessible site).
They're tempting as a quick-fix solution for accessibility compliance. It sounds appealingly simple - insert a snippet of code, and your website will be 100% accessible. However, these tools are very limited and do not constitute a full compliance solution. Some overlays even add new accessibility issues of their own, such as buttons that can't be used or no screen reader support.
If you'd like to learn more, the Overlay fact sheet (external site) explains it better than any summary could. The Overlay fact sheet explains all the reasons to avoid overlays. It also has quotes from the people overlays are meant to help: people with accessibility requirements.
How to support it
Simply - don't! Ensure that you're building accessibility into your designs and into your code, rather than relying on a 3rd party.