What Accessibility Scanners Can't Catch
An honest look at what automated accessibility testing finds, what it misses and why human testing matters.
Last reviewed by the WebsiteAccessibility.io team.
Key takeaways
- Automated tools reliably detect only a portion of WCAG issues; estimates commonly fall around 30–40%.
- Things like meaningful alt text, logical reading order and keyboard usability need human judgement.
- No scanner or overlay can make a site fully conformant on its own.
Start with what automation can find — then use our human checklist for the rest. Free homepage scan. Scan my homepage
Sources
- W3C WAI — Selecting web accessibility evaluation tools
- W3C WAI — Website Accessibility Conformance Evaluation Methodology (WCAG-EM)