WCAG 2.1 AA checks

6 min readLast updated 2026-04-27New

The specific WCAG 2.1 AA rules that Check Studio validates automatically.

Check Studio runs 42 automated WCAG 2.1 AA checks using axe-core. Here are the most impactful rules and how they are validated.

Color and contrast

  • color-contrast: Text must have 4.5:1 contrast against background
  • link-in-text-block: Links must be distinguishable from surrounding text

Navigation and focus

  • bypass: Page must have a skip link or landmark
  • focus-order: Tab order must follow visual layout
  • no-focus-traps: Focus must not be trapped in any element

Form labels

  • label: Every form input must have a label
  • aria-required-attr: Required ARIA attributes must be present
  • aria-roles: ARIA roles must be valid

Manual checks

Automated checks cover ~30% of WCAG 2.1 AA. Manual testing with screen readers is still required for full compliance.

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