For a financial product, a payment is not a feature on a list - it is the moment of truth. This is where the customer either completes the transaction or abandons the cart, and where you either reconcile balances to the cent or spend a week hunting for the discrepancy. Payment integration therefore decides conversion, trust and whether finance can close the day.
In our experience across banking and fintech projects, the hard part is not wiring up the first gateway, but keeping many payment methods, many providers and many standards inside one predictable whole that does not fall over at the first timeout. So this article is about how to build a payments layer that lasts for years, and who should be building it.
Why is payment integration so hard?
Because a payment is not one system but a chain of independent participants, each of which can fail on its own. Between the “Pay” click and the funds being booked, the flow passes through a gateway, an acquirer, a card scheme or a transfer system, the issuing bank and your own backend - and every link has a different SLA and a different way of reporting errors.
On top of that comes the sheer number of standards you must support in parallel: cards and 3-D Secure, instant transfers, local schemes, mobile wallets and, increasingly, open banking. Each standard carries its own rules for authorisation, refunds and disputes, and regulation (PSD2, SCA) layers extra requirements on top. Payment integration is therefore a project at the meeting point of technology, finance and compliance - and that meeting point is exactly where a single product team most often runs out of depth.
What are payment gateways and PSPs, and how do they differ?
It helps to separate four terms that blur together in business conversations:
- a payment gateway is the technical layer that accepts payment data, encrypts it and passes it on - the “plug” between your application and the settlement world,
- a PSP (payment service provider) gives you not just a gateway but also aggregation of many payment methods, settlement and reporting in one place,
- an acquirer handles the actual movement of money between banks,
- a payment orchestrator sits above the PSPs, letting you switch providers and route transactions without rewriting the integration.
The “one PSP or many” decision shapes the whole architecture: multiple providers call for an abstraction layer, so that adding another payment method does not mean rebuilding everything - and that layer is what we most often design with clients.
How do instant transfers work and which standards apply?
Instant transfers changed customer expectations: money should land in seconds, around the clock, weekends included. Technically, that means operating 24/7 with none of the maintenance windows that traditional banking once allowed itself. An instant payments system does not forgive downtime - the transaction either goes through immediately or the customer immediately knows something failed.
In Europe the organising standard here is SEPA Instant Credit Transfer, alongside local schemes in each market. Each of these systems imposes its own limits, message formats (increasingly based on ISO 20022) and confirmation rules. Our engineers approach this by designing the payment as an asynchronous process with explicit statuses, not as a single request - because that is the only honest way to handle both an instant success and a delayed confirmation or rejection.
How do you handle tokenisation and security (PCI DSS)?
Card data is material you are best off not holding yourself. The foundation of a secure integration is therefore moving sensitive data outside your own systems and shrinking PCI DSS scope to a minimum:
- tokenisation replaces the card number with a token that is useless to an attacker on its own,
- hosted fields and redirects keep card data from ever touching your server,
- encryption in transit and at rest protects what you do have to store,
- environment segmentation and access control cut down the scope of the PCI DSS audit,
- 3-D Secure and strong authentication (SCA) shift part of the risk to the issuer and satisfy the regulatory requirement.
PCI DSS compliance is not a one-off certificate but a way of designing the system. We lay out the architecture to keep the footprint of sensitive data as narrow as possible - the less card data flows through your systems, the cheaper the audit and the smaller the attack surface.
How do you ensure reliability, error handling and reconciliation?
You only see this part once something goes wrong, which is exactly why it is so easy to overlook. A payment is distributed, so you have to assume a response will get lost, arrive late or arrive twice. We design operations to be idempotent, with a unique transaction key, so that retrying a request never charges the customer twice and every status can be rebuilt from the log.
The other half of this work is reconciliation: the daily matching of what your system sees against what the PSP and the bank report. Without it, balances start drifting apart and disputes pile up. We build automatic transaction matching, discrepancy reports and a clear path for refunds and chargebacks, plus monitoring and alerting at the level of a single payment method - because one gateway failing should not look like a failure of the whole product.
Which skills do we provide for a payments project?
We have no single recipe for team shape here - we match the lineup to the stage and architecture. Most often we staff the roles that genuinely decide the quality of the payments layer:
- backend developers (Java, .NET, Node) building integrations with gateways, PSPs and transfer systems,
- a solution architect designing the abstraction over providers and the transaction model,
- DevOps / SRE specialists owning reliability, monitoring and 24/7 operation,
- QA engineers testing error paths, timeouts, refunds and reconciliation,
- security and compliance skills supporting PCI DSS and regulatory requirements.
An important caveat: we are writing here about competence, not an off-the-shelf payments product. We provide the people who will build it - engineers experienced in banking and fintech projects, plugged into your team and your processes.
How fast can a team join a payments project?
Speed matters, because the market window for a new payment method can be short. As a nearshore partner from Poland we work in a close time zone, so our specialists join your rhythm of code reviews and meetings without a long ramp-up. We usually close the staffing process in around three weeks and verify skills before the start - with payments, experience in regulated projects is not something to take on trust.
How do we do it at RITS?
We do it as a nearshore partner from Poland that adds skills where they are missing and takes ownership of a slice of the system:
- we staff the roles of backend, architecture, DevOps and QA around your specific payments architecture,
- we design the abstraction layer over gateways and PSPs, so switching a provider is not a rewrite,
- we automate reconciliation, refunds and error handling, and plug the team into your processes and tools.
Most often this is custom software built by our team and, where skills need topping up fast, team augmentation.
Where to start with payment integration?
Start from the single most important payment path (e.g. a card payment with 3-D Secure or an instant transfer) and from the question of what reconciliation will look like for it. That drives your choice of PSP, your transaction model and the roles you need. We covered the differences between engagement models in our article on IT engagement models.
Building or rebuilding a payment integration? Let’s talk - we’ll match a team and an architecture to your financial product.