Short answer: - Prefect Cloud webhooks are subject to Prefect Cloud’s API rate limits. If you exceed them you’ll get HTTP 429 with a Retry-After header. - Prefect Server (self-hosted) does not document built‑in rate limits; any limits would come from your own gateway/load balancer. Prefect Cloud 3.x limits by plan (requests per minute) - Hobby: 250 rpm (~4 rps) - Starter: 500 rpm (~8 rps) - Team: 1,000 rpm (~17 rps) - Pro: 2,000 rpm (~33 rps) - Enterprise: custom Docs: Prefect Cloud rate limits. Webhook behavior: Webhooks. What happens on limit - Exceeding the limit returns 429 Too Many Requests with a Retry-After header indicating how long to wait before retrying. Recommendations - Respect Retry-After and implement exponential backoff with jitter for retries. - If you expect bursts above your plan’s rpm, buffer on your side (queue) and drip feed to Prefect within your sustained throughput budget. - Keep payloads small and idempotent so retries are safe. - If you regularly need more throughput, consider upgrading your plan or contact support. If you can share whether you’re on Prefect Cloud or self-hosted Server (and your plan/expected peak rps), I can suggest concrete backoff settings and buffering targets.