All WCAG criteria
WCAG 2.3.1 · OperableLevel A

2.3.1Three Flashes or Below Threshold

Content must not flash more than three times in any one-second period (to avoid triggering photosensitive seizures).

Common failures

Patterns that fail this criterion.

  • 01Strobe-effect promotional banners
  • 02Rapidly blinking notification badges
How to test

Testing approach: manual.

Manual or use the PEAT tool (Photosensitive Epilepsy Analysis Tool).

How to fix

Remediation steps.

  1. 1

    Limit flashing

    No more than 3 flashes per second. If unsure, slower is safer.

  2. 2

    Avoid strobe effects entirely

    They rarely add UX value worth the seizure risk.

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WCAG 2.2.2 · Level A

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All 50 WCAG 2.1 Level A + AA success criteria explained.

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