Shopify allows a 10 second window for a response back to the store. The carrier response may not take more than 5-7 seconds.
Ten seconds is the total window of time that Shopify allows for 3rd party negotiated rates to be returned and calculated according to Merchant settings. There are many operations that have to be performed in addition to the negotiated rate. For example: the address type has to be confirmed, Standard Box Sizes (SBS) must run when enabled, the Google Cloud Platform has to be consulted to get the distances so the right warehouse is selected, etc. All of these are separate API transactions in addition to the carrier's response.
When the carrier's API response time is..., the probability of a shipping rate response is...
5 seconds or less: Very high
6 seconds: High
7 seconds: Low to medium
More than 7 seconds: Unlikely
To view the amount of time the carrier is taking to respond to rate requests, enable the "Logs" feature in the app. Consult the User's Guide for instructions.
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