Inconsistent / Delayed Responses from Amazon SP-API Batch Endpoints at Scale

[ihtishamtanveer]

I’m experiencing inconsistent and significantly delayed responses when using Amazon SP-API batch endpoints at scale. The issue becomes noticeable when processing large datasets (40–50k items) across multiple users/accounts.

Use Case

I’ve built a catalog ingestion and enrichment service where:

• Vendor catalog files (CSV/XLSX) are processed

• Items are enriched using Amazon SP-API

• The system runs concurrently for multiple users

• Data volume per run is ~40–50k items

The system works fine for small datasets and single users, but once concurrency and volume increase, API behavior becomes unstable.

APIs Involved

• searchCatalogItems

• getItemOffersBatch

• getFeesEstimateBatch / feesListingBatch

Observed Issues

• Batch calls start taking significantly longer than expected

• Responses are inconsistent (some batches succeed, others are delayed or fail)

• Latency increases progressively during long-running jobs

• Even when staying within documented rate limits, behavior degrades at scale

Architecture Notes

• Calls are distributed via SQS queues to manage throughput

• Rate limits and backoff strategies are implemented

• Requests are spread across multiple seller accounts / users

• Batch sizes are kept within documented limits

Questions

• Are there undocumented throttling rules or internal limits for batch endpoints when used at high volume or concurrency?

• Is there a known issue or best practice for running batch APIs across multiple sellers simultaneously?

• Are batch APIs internally queued or deprioritized compared to single-item endpoints?

• Has anyone observed similar latency or inconsistency when processing tens of thousands of items?

• Any recommendations on:

  • Optimal batch sizes

  • Preferred retry strategy

  • Whether single-item calls are more reliable at scale than batch APIs

Goal

Looking to understand whether this is:

• Expected SP-API behavior at scale
• A known limitation of batch endpoints
• Or an architectural issue that needs a different approach

Any insights, official guidance, or real-world experience would be greatly appreciated.

[ritikacd]

Hi @ihtishamtanveer

Are you seeing delayed responses from all three endpoints or a specific one?

Please note Catalog Items API have multiple rate limits - selling partner account- application pair and also on the application that calls the Selling Partner API on behalf of the selling partner account. Requests are rate-limited by whichever threshold you reach first. Make sure you are accounting for both the rate limits.

Thanks,
Ritika