Rate limits - LetterBucket knowledge base

Requests are rate limited per API key across three independent windows — minute, hour and day. If any window is exceeded, the API returns 429.

Limits

Window	Default	Bulk create (`POST /subscribers/bulk`)
Per minute	60	10
Per hour	500	100
Per day	3000	500

Limits are tracked per API key. Always respect the Retry-After header on a 429 before retrying.

429 Too Many Requests

{
  "success": false,
  "code": "rate_limit_exceeded",
  "message": "Too many requests. Please try again later.",
  "errors": { "retry_after": 42 }
}