Customer.io · Rate Limits

Customer Io Rate Limits

Customer.io exposes three primary APIs (Track, App, Pipelines / CDP) with per-workspace rate limits. Documented limits are not currently published as fixed numeric thresholds in public docs; Customer.io throttles via HTTP 429 with Retry-After. Track API is optimized for high-throughput event ingestion; App and CDP have lower default budgets.

4 Limits Throttle: 429 Quota: 429
Customer Data PlatformMarketing AutomationMessagingRate LimitingQuotasThrottling

Limits

Track API (event ingestion) workspace
requests_per_second
see Customer.io API reference (high-throughput ingestion)
App API (campaigns / broadcasts / segments) workspace
requests_per_second
see Customer.io API reference
Pipelines (CDP) API workspace
requests_per_second
see Customer.io API reference
Per-workspace email send budget workspace
emails_per_month
tied to plan (1M included on Essentials; custom on Premium / Enterprise)

Policies

Backoff Strategy
On 429, honor the Retry-After header (seconds). Use exponential backoff with jitter on additional retries.
Bulk-friendly endpoints
Use the batch identify and batch event endpoints rather than tight loops of single calls to stay within ingestion budgets.
Plan-tied volume caps
Email volume caps are set by plan (Essentials 1M / Premium custom / Enterprise custom); overage is metered, not throttled.
Soft-vs-hard limits
Soft rate caps return 429 and recover on Retry-After; sustained over-cap traffic may trigger workspace-scoped backpressure.

Sources