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Version: Next

TTS Rate Limiting

This page explains OpenReader's TTS character rate limiting controls.

Overview​

  • TTS rate limiting is disabled by default.
  • To enable it, set TTS_ENABLE_RATE_LIMIT=true.
  • Limits are enforced per day in UTC.
  • Enforcement applies only when auth is enabled.

How enforcement works​

When enabled, OpenReader enforces:

  • Per-user daily character limits.
  • IP backstop daily character limits.
  • Anonymous device backstop tracking (cookie-based) to reduce limit resets.

If a request exceeds the active limit, the TTS API returns 429 with reset metadata for the next UTC day.

Required auth behavior​

  • Auth must be enabled (BASE_URL + AUTH_SECRET) for TTS char limits to apply.
  • If auth is disabled, TTS character limits are effectively unlimited.
  • DISABLE_AUTH_RATE_LIMIT only affects Better Auth's own request throttling.
  • DISABLE_AUTH_RATE_LIMIT does not disable TTS character limits.

Environment variables​

Enable/disable:

  • TTS_ENABLE_RATE_LIMIT (default: false)

Per-user daily limits:

  • TTS_DAILY_LIMIT_ANONYMOUS (default: 50000)
  • TTS_DAILY_LIMIT_AUTHENTICATED (default: 500000)

IP backstop daily limits:

  • TTS_IP_DAILY_LIMIT_ANONYMOUS (default: 100000)
  • TTS_IP_DAILY_LIMIT_AUTHENTICATED (default: 1000000)