Rate limits
Authenticated requests are governed by your credit balance — there is no separate per-minute cap. A request that would exceed your balance returns 402 NO_CREDITS.
Without a key
Read, Map, Enrich, and Images can be tried without a key, subject to a per-IP limit (roughly 15 requests per minute). Extract, Classify, and Crawl always require a key and return 401 AUTH_REQUIRED when called anonymously.
Backing off
When you exceed a limit you receive 429 RATE_LIMITED. Back off and retry, honoring the Retry-After header when present. Authenticated keys get far higher throughput than anonymous traffic.