Payment Gateway

What is a payment gateway?

A payment gateway is the technical layer that encrypts and passes payment data from your store’s checkout on to the acquirer and payment processor, so a card payment can be approved or declined. It handles the transport and authorization of the data — not the actual movement of money, which the acquirer and card networks handle. A gateway is often confused with a PSP, but a PSP usually bundles the gateway, processing, and acquiring into a single contract.

Why does a payment gateway matter?

The gateway is the last link before the money — and a common place where sales are lost. Timeouts, poor error handling, or missing payment methods lead to declined payments and higher drop-off in checkout. A stable gateway with local payment methods (cards, MobilePay, Apple Pay) and clear error messages directly improves the completion rate.

Common use cases

• Authorizing card payments in real time when the customer clicks “Buy”.
• Supporting 3D Secure / SCA so payments comply with PSD2.
• Adding local payment methods like MobilePay, Klarna, or Apple Pay.
• Handling declined payments with useful error messages instead of a blank failure.
• Tokenizing card data for subscriptions and repeat purchases.

Shopify perspective

Shopify Payments is the store’s built-in gateway and processor (built on Stripe’s infrastructure). If you use a third-party gateway instead, Shopify charges an extra transaction fee (typically 0.5–2% depending on your plan) on top of the gateway’s own fees. Shopify supports over 100 third-party gateways, but in Denmark most stores choose either Shopify Payments or a local provider such as Quickpay or Nets. Always test a real purchase in each payment method before going live.