Integration is more than calling an API
Connecting a gateway so that a test card works takes an afternoon. Making it reliable takes engineering: handling timeouts, duplicate webhooks, partial captures, refunds, disputes and settlement files. Ask the partner how they treat each of these.
A good answer mentions idempotency keys, signed webhooks, a payment state machine and a reconciliation job that compares your records with the provider’s.
Provider and local method coverage
Your customers pay differently by country: cards, bank transfers, wallets, instant payment schemes and cash vouchers. Choose a partner who has integrated the providers relevant to your markets and can explain trade-offs in fees, approval rates and settlement times.
If you expect to grow, ask about payment orchestration: routing between several providers so one outage or a poor approval rate does not stop revenue.
PCI scope and security
Good design keeps card data out of your servers, using hosted fields or tokenization so your PCI scope stays small. Confirm how secrets are stored, how access is logged and how the integration is tested before it handles live money.
A scorecard for integration partners
Rate partners on provider and local-method coverage, reliability engineering (idempotency, webhooks, retries), PCI scope management, reconciliation tooling, routing and failover design, and how clearly they explain fees and approval-rate trade-offs. Reliability and reconciliation matter most once real money flows.
Payment integration partner comparison at a glance
| What to check | A strong answer | A warning sign |
|---|---|---|
| Failure handling | Idempotency, retries, a payment state machine | Only the happy path is tested |
| Provider coverage | Has integrated the providers your markets use | Knows one provider well |
| Card data scope | Hosted fields or tokenization keep card data off your servers | Card numbers pass through your backend |
| Reconciliation | Settlement files matched automatically | Finance matches payments by hand |
| Resilience | Routing and failover between providers | Single provider, no fallback |
Questions to ask in the first call
Ask what happens when a webhook arrives twice, or never arrives; how a payment stuck in pending is resolved; and how refunds and chargebacks reach your ledger. Ask which providers they have integrated in your target countries and what went wrong the last time.
- Ask what happens when a webhook arrives twice, or never arrives.
- Ask how a payment stuck in pending is resolved.
- Ask how refunds and chargebacks reach your ledger.
- Ask which providers they have integrated in your target countries.
- Ask how test-mode behaviour differs from production in the providers you use.
Phases of a gateway integration
A sound project includes a payment flow design, sandbox integration, state machine and ledger mapping, webhook and retry handling, security review, a pilot with real low-value transactions, and monitoring dashboards. Reconciliation against settlement files is part of the build, not an add-on.
Mistakes buyers make
Common mistakes are integrating one provider with no fallback, storing card data when tokenization would do, ignoring local payment methods that dominate a market, and assuming test-mode behaviour matches production. Each leads to lost revenue or avoidable compliance burden.
How NNT Software approaches payment integrations
We connect providers, bank rails and wallets behind a single payment layer with signed webhooks, idempotency keys, routing options and automated reconciliation. We respond to every enquiry within 10 minutes, set up a meeting to understand your requirements, share a demo within 24 hours of that meeting, and then send a proposal that matches your budget.
Integrations ship with monitoring for failed, pending and mismatched payments, so problems surface before customers report them. A free 90-day defect warranty follows go-live and a support agreement can continue from there.
Example scenario: adding local payment methods to a checkout
Illustrative scenario, not a client case: an online store that accepts cards through one provider wants to add bank transfers and a wallet popular in a new market. A careful partner first maps the payment states for each method, since a bank transfer settles later and can fail after the customer has left the page.
The work puts a single payment layer in front of the providers, with signed webhooks, idempotency keys so a retried request never charges twice, and a reconciliation report that matches each order to the provider’s settlement. New methods are switched on for a small share of traffic first and widened as failure rates stay low.
Red flags to walk away from
Avoid a partner who stores card data on your servers when tokenization would do, or who has never handled a settlement mismatch. Both lead to avoidable compliance burden and finance work.
Treat a plan with one provider and no fallback as a business risk, not a detail. A single outage then stops all revenue.
Pricing and engagement model
NNT Software’s rates are US$15–40 per hour; the final cost depends on how many providers and payment methods you need, the timeline and the team assigned. Ask for a fixed discovery phase, then a scoped estimate, so the cost reflects your real requirements and budget.
Sources and further reading
More buyer guides
How NNT Software delivers projects like this
- Discovery — workshops, requirements and a written scope with a fixed estimate within days.
- Design — user flows, a clickable prototype and an architecture review before coding starts.
- Build — two-week sprints with demos, a shared backlog and code in your own repository.
- Test — dedicated QA, automated regression tests, performance and security checks.
- Launch — zero-downtime deployment, monitoring and user training.
- Support — SLA-backed maintenance and continuous improvement after go-live.