Comparison
Accessibility overlays vs fixes in your HTML
We make Fixlight, so we're not neutral. We wrote this page to be checked: every fact about another product links to its source and says when we read it. If something is wrong or out of date, write to fixlight@fernwaylabs.com and we'll fix it.
There are two ways a tool can fix accessibility problems without you editing your site: change the page in each visitor's browser after it loads (an overlay), or change the HTML on your server before it's sent. Here is what that difference means, and what the evidence says.
The two approaches
Overlays: a script that changes the page in the browser
An overlay is code, usually JavaScript from the vendor's servers, that changes a site's front end after it loads, often with a menu for visitors to adjust text size or contrast.source [1] accessiBe, UserWay and AudioEye work this way on WordPress: their plugins add the vendor's script to every page.source [8]source [9]source [10]
Fixes in your HTML: the page is fixed before it's sent
The other way is to fix the page on your server, so every visitor gets the corrected HTML: screen readers, search engines and browsers with JavaScript turned off see the same fixed page. Fixlight works this way. So do parts of other plugins:
- Elementor's Web Accessibility plugin applies fixes you saved for scanned pages to the HTML on the server, alongside its visitor widget, which is on by default.source [11]
- WP Accessibility and Equalize Digital's Accessibility Checker make some fixes on the server and some with a small script of their own.source [12]source [13]
| Compared | Overlay (in the browser) | Fixes in your HTML (on the server) |
|---|---|---|
| Visitors load | The vendor's script, on every page | Nothing extra (Fixlight adds a little CSS) |
| Works without JavaScript | No | Yes |
| Visitor menu (text size, contrast) | Usually | Usually not |
| Your content and theme files | Not changed | Not changed (the page is fixed as it's sent) |
| Turning it off | Remove the script | Switch the fix off; it's undone at once |
What the evidence says
- Practitioners: in WebAIM's 2021 survey of 758 accessibility practitioners, 67% rated overlays and similar tools "not very" or "not at all" effective. Among respondents with disabilities it was 72%. WebAIM notes the sample wasn't controlled.source [3]
- The Overlay Fact Sheet, with over 1,000 signatories, says overlays can't make a site fully compliant with any standard or remove legal risk, and that automated repair is unreliable for alt text, labels, focus and keyboard access.source [1]
- The National Federation of the Blind resolved in 2021 that overlays can't on their own guarantee full nonvisual access, and condemned marketing that sells them as the easiest protection from lawsuits.source [2]
- Automated error counts: in the WebAIM Million 2024, home pages with AudioEye, UserWay or accessiBe averaged fewer detected errors (36.9, 42.9 and 50.5) than home pages overall (56.8). That is a plain correlation, and automated tools can't detect every failure.source [4]
- Lawsuits: UsableNet, a company that sells accessibility services, reported that 1,023 companies with an accessibility widget on their site were sued in 2024.source [5] Its 2025 report's monthly chart adds up to 1,416 lawsuits against companies using widgets, out of about 5,100 cases it reviewed. The report doesn't say how it detected the widgets.source [6]
- Marketing claims: in 2025 the FTC ordered accessiBe to pay $1 million over claims that its automated tool could make any website WCAG compliant.source [7]
What neither approach can do
No automated tool, overlay or not, can make a site fully accessible or "compliant" with a law on its own. Both can handle common, mechanical problems. Colour choices, captions, meaningful alt text for new images, complex widgets and many keyboard problems need a person. A good tool tells you what's left.
Where Fixlight fits
Fixlight is a free WordPress plugin that makes 17 fixes in your site's HTML as pages are sent, checks your pages, and explains what's left in plain words. It has no visitor menu and loads no script for visitors. See five of the fixes, with a switch for each. Already decided to leave a widget? How to cancel and remove each one.
Try Fixlight on your own site
Free, with no account, no page limits and no script for your visitors. Turn any fix off and it's undone at once.
Sources
Checked on October 22, 2026. Prices and numbers change; each link goes to the page we read.
- Overlay Fact Sheet. Signatories counted by us on the checked date; the page shows no total.
- National Federation of the Blind: 2021 resolutions, including 2021-04 (overlays) and 2021-17 (accessiBe)
- WebAIM: Survey of Web Accessibility Practitioners #3 (January 2021)
- WebAIM Million 2024. The 2025 and 2026 editions have no overlay comparison.
- UsableNet: 2024 Year-End ADA Web Lawsuit Report (PDF)
- UsableNet: 2025 Year-End Digital Accessibility Lawsuit Report (PDF). The yearly widget total is our sum of its monthly chart; UsableNet prints no total.
- FTC: final order requiring accessiBe to pay $1 million (press release, April 22, 2025)
- Web Accessibility by accessiBe on WordPress.org. Install and rating numbers from the WordPress.org plugin API. The plugin version 2.13 adds a script from acsbapp.com to every page.
- UserWay: WordPress installation guide
- Accessibility by AudioEye on WordPress.org
- Web Accessibility (formerly Ally / One Click Accessibility) by Elementor on WordPress.org. Version 4.1.4: the widget loads from cdn.elementor.com unless turned off; saved fixes are applied to the page on the server for scanned URLs.
- WP Accessibility by Joe Dolson on WordPress.org
- Accessibility Checker by Equalize Digital on WordPress.org