First Data (Fiserv) · Rate Limits

First Data Rate Limits

Fiserv (parent of First Data) does not publish numeric rate limits for Commerce Hub or other developer APIs. Production throttling is set per merchant agreement and capacity profile. Standard HTTP 429/503 throttling responses apply, and idempotency is supported via Client-Request-Id headers on Commerce Hub APIs.

1 Limits Throttle: 429
PaymentsMerchant ServicesFinancial ServicesTransaction ProcessingRate Limiting

Limits

Commerce Hub / Carat per-merchant throttle merchant/api-key
varies
per-merchant agreement; not publicly published

Policies

Idempotency
Commerce Hub supports idempotency via Client-Request-Id; retries with the same key return the original response within the idempotency window.
Backoff Strategy
Clients should implement exponential backoff with jitter on 429 / 5xx responses and honor Retry-After when present.
Per-Merchant Throttling
Throttles are sized per merchant onboarding; raise limits via Fiserv account/support team rather than self-service.
Settlement Cutoff Pressure
Volume near daily settlement cutoffs may experience tighter throttling; size batches and retries accordingly.

Sources