All WCAG criteria
WCAG 1.2.4 · PerceivableLevel AA

1.2.4Captions (Live)

Live audio (webinars, livestreams, real-time video calls) must include captions in real time.

Common failures

Patterns that fail this criterion.

  • 01Live product launches streamed without live captioning
  • 02Webinars relying solely on auto-captions (often inadequate for live)
How to test

Testing approach: manual.

Manual — observe a live event and confirm captions appear in sync.

How to fix

Remediation steps.

  1. 1

    Live caption services

    Use professional re-speakers (CART) or AI-assisted services (Otter, Rev, AWS Transcribe). Accuracy matters more than free.

  2. 2

    Test before going live

    Run a 5-minute dry run at full quality before the real event. Caption latency must be under 3 seconds.

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Related criteria

Often appears with…

WCAG 1.2.2 · Level A

Captions (Prerecorded)

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

View the full checklist