Third-party payment systems used on Shopify, such as Craftgate or iyzico, are activated only during the payment stage, thus preventing them from accessing the details of items in the shopping cart. This limitation poses a significant challenge, particularly for retail brands selling electronic products. For instance, a brand may wish to offer installment plans selectively—for example, not providing installments for certain products like Apple iPhones, while allowing them for other products. However, since the payment systems cannot access cart contents, it becomes impossible to implement product-based installment plans.
Currently, these third-party payment systems utilize Shopify’s provided endpoint at Payments app request reference, which returns only a redirect_url in the response body. If Shopify could include the cart ID information within the response body of this endpoint, we could develop middleware software to resolve the product-based installment issue using systems like Craftgate or iyzico.
We are seeking guidance on how we can proceed with this solution.