The Maksukaista NodeJS SDK by PayByWay can access the API to integrate payments into merchant applications. Functions allow adding charge, customer, product, payment method, token status, and card token.
Shopify has replaced its legacy Discounts API with the New Price Rules API. The API keeps what worked from the Discounts API, and greatly enhances those features with more flexibility and capability. One and five Shopify sales includes a discount of some sort, and Shopify wants to capitalize.