I am developing a web page to collect Cardholder info and make a request to a Shopify API to process a sale transaction. I don’t want to use the Shopify UI components. Is there a Shopify API to support this?
I would like to process MOTO transactions as well as online using Shopify’s Payment Processor.
What you’re describing would likely require building a Payment Extension to integrate custom payment processing. You can find the documentation here: Building Payment Apps. However, applications for new payment apps are currently invite-only.
Draft Orders may be a better solution for your use case. You can create a draft order via the Admin API with customer and product details, then either email a secure invoice link to your customer (they complete payment on Shopify’s secure checkout) or manually enter card details in the Shopify admin for true MOTO scenarios.