Na Oku is the web app Erste Card Club's clients use to manage and monitor their card transactions. Moberg rebuilt its backend from scratch — while the people relying on it kept using it — and now maintains the whole application.
Erste Card Club, now part of Global Payments, is a Croatian card and payments company with decades of history in the market — long associated with Diners Club in Croatia. Its clients expect what card clients everywhere expect: to see their transactions, understand their spending, and trust that the numbers on screen are the numbers on record.
Na Oku — "keeping an eye on it" — is the web application where that happens. Moberg's engagement was the complete development of a new backend for Na Oku, together with optimisations across the application. The frontend has since joined the backend under Moberg's care: today Moberg maintains the full stack of the product.
The defining constraint of this project was that Na Oku was not a greenfield. Real clients were monitoring real transactions through it every day, and "we're rebuilding the backend" is not a message a payments company sends its customers. The new backend had to be developed, proven and put into service under a live product — modernising the engine without interrupting the people driving.
Moberg built the new backend on Azure, which fits both the workload and the setting: a card-industry client needs the security posture, auditability and operational maturity of a major cloud, not a bespoke hosting story. The frontend is Angular — a framework whose structure suits long-lived enterprise applications maintained by changing hands over years.
Alongside the rebuild came optimisations: the unglamorous work of making an application that displays financial data feel fast and behave predictably. In transaction monitoring, performance is not a luxury feature — a slow answer to "what did I spend?" reads as an untrustworthy one.
Card clients check their transactions daily. Replacing the backend beneath them means the switchover has to be invisible — the product cannot blink while its engine is swapped.
A transaction shown wrong, doubled or missing is not a UI bug in this industry — it is a support call and a dent in confidence. The new backend had to match the old one's answers before it could improve on them.
Building for a Global Payments company means inheriting the security, compliance and process expectations of the payments world. The engineering has to hold up to review, not just to use.
Erste Card Club got a modern backend under a product its clients never stopped using — the rebuild happened around them, not to them. The move to a from-scratch backend on Azure converts accumulated legacy into a platform that can be extended and optimised deliberately, instead of one that is negotiated with.
The engagement's current shape is its own argument: Moberg now maintains both backend and frontend. One partner accountable for the whole application means no seam between "their part" and "our part" when something needs fixing — and in a financial product, things that need fixing rarely announce which layer they live in.
The new backend — built for the security, auditability and operational standards a payments company answers to.
The client-facing application — a structured framework suited to enterprise products maintained for years.