I see that non-Shopify Plus accounts don't have the option to mass load gift cards that were previously issued using a different service.
Is it feasible to upgrade to Shopify Plus for the shortest possible period of time, upload all gift cards via a private app calling the gift card API, then downgrade back to the $79/mo plan?
There is no need to do those changes in your account!
you can use our app - Rise.ai.
In addition to many other features, you can create Bulk Gift Cards in just a few clicks!
Here is an article from our help center
You should check our gift card solution I think you might like it.
Feel free to reach out with any questions at email@example.com
You can essentially grab this app and it will allow you to bulk create 10,000 gift cards on the cheap. It exports all the CSV so you can then do what you'd like and then downgrade back to your lower Shopify account.
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