OnPay · gateway
OnPay integration in your web app
An OnPay integration means checkout in your system creates a payment at OnPay and only marks the order paid when their notification is verified. Danish shops use OnPay when they want a sober gateway layer without a huge product suite. That is fine when you have one currency, one flow and an existing agreement. Amounts are set server-side. The callback signature is verified. Timeout: the customer closes the window, and your order must not hang in “pending” forever without a cleanup job. Refunds are logged with a user id in your admin. If you do not have an agreement yet, choose based on MobilePay need and the support you want to call.
7 min read · Updated 28 August 2026
If you already have OnPay, start there. A new gateway is KYC and first settlement on top of the build. Payments.
Build rules for an OnPay integration
- Amount is set server-side
- Callback signature is verified
- A timeout job clears orders that hang in pending
- Refunds are logged with a user id in your admin
Create payment
The backend sends amount, currency and order id to OnPay.
Window
The customer pays or closes. Close is not the same as declined.
Callback
You verify the signature and write status. Only then is the order paid.
Cleanup
A job finds orders that never got a callback and returns them to the cart.
OnPay or QuickPay
If you do not have an agreement yet, choose by MobilePay need, settlement and the support you want to call. If you have OnPay, start there. QuickPay integration is the comparison, not an automatic upgrade.
OnPay in a Ceptiv package is 1 integration. Small 18,000 DKK + 600 DKK/month. The transaction fee is OnPay’s.
Hanging orders and the timeout job
What separates a finished OnPay integration from a demo link is the job that clears “pending” after 30–60 minutes and gives the customer a way back. Write it in the brief. Get a quote · Pricing.
FAQ: OnPay integration
OnPay or QuickPay?
Can we trust that the customer returns in the browser?
What happens if the customer closes the window?
Want us to build it for you?
You get a fixed-price proposal within 24 hours.
