Automated vs Manual Accessibility Testing

Automated accessibility scanners reliably detect roughly 30 to 40 percent of the WCAG success criteria. That number surprises people who bought a tool expecting a green checkmark, but it has held steady across independent research for years. It isn't a knock on any particular scanner — it's a hard limit of what a machine can decide by reading code without understanding meaning, context, or intent.

So anyone who tells you a scan alone makes you compliant is selling you something. And anyone who tells you automated testing is worthless is also selling you something — usually a very expensive audit. The truth is that the two methods are complementary, not competing. One gives you breadth and speed at near-zero marginal cost; the other gives you judgment. Skip either and you have a blind spot.

The other 60-plus percent of WCAG is where machines run out of road. These criteria require a judgment call about meaning or experience, and no amount of clever code can make that call for you:

• Whether alt text is correct. A scanner confirms an image has alt text. It cannot tell you that “image123” is a useless description, or that a decorative photo should have been marked as decorative instead.
• Whether the reading and focus order make sense. The DOM can be technically valid and still present content in an order that's nonsense to a screen-reader or keyboard user.
• Whether a keyboard user can actually complete a task. Focus traps in modals, custom dropdowns you can open but not close, and skipped interactive elements almost always need a human at the keyboard to find.
• Whether link text and instructions are meaningful. Ten “click here” links pass every automated check and fail a real user completely.
• Whether error messages, video captions, and dynamic updates genuinely work for someone relying on assistive technology.

This is the honest reason we don't claim any tool — ours included — can make you “compliant” or “lawsuit-proof.” Compliance is a property of the experience a real person has, and part of that can only be verified by a real person. For the full picture of what a proper evaluation involves, see our accessibility audit guide.

The most cost-effective program uses each method for what it does best. Automated first, manual second, monitoring always:

1. Scan everything, automatically. Run every template through a scanner to clear the deterministic 30–40% at scale. Start with our free WCAG checker or the ADA compliance checker to get a baseline in minutes. Fixing these first means your human testers don't waste their time on issues a machine could have flagged.
2. Manually test what the scan can't see. Point your human effort — yours or an expert's — at keyboard flows, screen-reader experience, and the quality of alt text and link text. This is where the remaining 60% lives.
3. Use AI to speed up remediation, not to decide it. CompliaScan's AI fix suggestions are bring-your-own-key — you plug in your own OpenAI, Anthropic, or Gemini API key and pay the provider directly, with no markup from us. AI can draft an alt-text suggestion or a code fix in seconds, but a human still confirms it's right before it ships.
4. Re-scan on a schedule. Sites change constantly, and a fix today can regress next deploy. Continuous automated monitoring catches new regressions cheaply so you only re-run the pricey manual pass when something structural changes.