The short answer
Payment gateway integration services means wiring a payment provider into your product so money moves, state stays correct and every transaction can be traced later. In practice that is four things: a checkout flow your customers finish, a webhook listener that survives retries and out of order delivery, idempotency so a double click or a network timeout never charges twice, and a reconciliation view that matches what the gateway settled against what your database says it owes. We build all four. We work with Stripe, Adyen, Braintree and PayPal, and we also build directly against African rails: Paystack, Flutterwave, M-Pesa and MTN MoMo.
That combination is the reason clients come to us. Plenty of firms can wire up Stripe. Far fewer have shipped an M-Pesa STK push that handles the customer who ignores the PIN prompt for ninety seconds, or a MoMo collection callback that arrives twice with different statuses. We have. Most payment integration projects land , quoted fixed before work starts, on a 50/25/25 payment plan. We have 29 live builds behind us and manage over $100k in client ad spend, so we see exactly what happens to conversion when checkout breaks.
Why payment integration is the part that bites
Every other feature in your product fails quietly. Payments fail loudly, in public, with someone's money in the middle. A broken profile page annoys a user. A broken charge flow produces a support ticket, a chargeback, a refund request and a finance team that no longer trusts your numbers.
The failures are rarely in the happy path. The happy path takes a day. What takes real engineering is everything around it.
- The customer's card is charged, then your server dies before writing the order. The gateway says paid. Your database says nothing happened.
- The webhook arrives twice, or three times, or out of order, and your order jumps from fulfilled back to pending.
- A mobile money callback lands eleven minutes late because the telco queue backed up, long after your session timed out.
- A refund is issued by hand in the gateway dashboard and your system never hears about it.
- Month end arrives and nobody can explain the gap between the settlement file and your revenue report.
We design for those cases first and build the happy path around them. That is the whole difference between an integration that works in a demo and one that still works in month fourteen.
What a proper integration includes
Every build is scoped to your product, but this is the spine of the work.
Checkout and charge flow
Hosted fields or a hosted page where it makes sense, so card data never touches your servers and your PCI scope stays at SAQ A. Where you genuinely need a custom form, we will tell you what that costs you in compliance terms before you decide, not after.
Idempotency and state
Every charge carries an idempotency key. Every payment has an explicit state machine with recorded transitions, so you can answer the question what happened to this order from data rather than guesswork. Retries are safe by construction.
Webhooks that survive reality
Signature verification, replay protection, a durable queue, dead letter handling and manual replay from an admin screen. Webhooks are treated as the source of truth for payment state, never the browser redirect.
Refunds, disputes and payouts
Partial and full refunds from inside your own admin, dispute evidence hooks, and payout tracking so you know which settlement batch a given order landed in.
Reconciliation
A daily job that pulls the gateway's settlement data and diffs it against your ledger, flagging anything that does not tie out. This is the feature most teams skip and most finance departments beg for. If your payments feed internal systems, we extend the same discipline into custom HRM software development and finance modules through API development and integration.
Cards and African rails, in one build
Most products that sell across borders need two different kinds of payment thinking at once, and the two behave nothing alike.
Card and wallet gateways
Stripe for speed of build, strong tooling and SCA handling. Adyen when you need one platform across many countries with local acquiring and detailed settlement reporting. Braintree where PayPal and Venmo matter to your buyers. PayPal as a trust layer in markets where buyers hesitate to hand over a card. These are request and response systems: you charge, you get an answer in seconds, 3DS steps in when the issuer wants it.
African rails
Paystack and Flutterwave for cards, bank transfer and mobile money across Nigeria, Ghana, Kenya, South Africa and beyond. M-Pesa Daraja for STK push, C2B and B2C payouts in Kenya and Tanzania. MTN MoMo and Airtel Money collections in Uganda and across the region.
Mobile money is asynchronous and human paced. You push a prompt to a phone, then wait for a person to find their handset, read the message and type a PIN. They might do it in eight seconds. They might do it in four minutes, or never. The callback may arrive out of order, arrive twice, or not arrive at all, which is why status polling as a fallback is not optional. Building this well takes experience with the specific rail, not a generic SDK wrapper. Our mobile money integration services page goes deeper on that side, and the mobile money integration guide explains the mechanics in plain terms.
Few Western agencies can do both halves. Few local shops can do the Adyen half. We do both, and that is why this page exists.
What payment gateway integration costs
We quote fixed before work starts. No hourly meter, no scope creep invoice at the end. Payment is 50 percent to begin, 25 percent at the review build, 25 percent on delivery.
| Scope | Typical investment | What you get |
|---|---|---|
| Single gateway, standard checkout | One provider such as Stripe or Paystack, hosted checkout, verified webhooks, idempotent charges, refunds from your admin | |
| Multi gateway with routing | Two or more providers behind one internal payment interface, currency and country routing, unified transaction log, retry on provider failure | |
| Cards plus mobile money | Card gateway plus M-Pesa, MoMo or Flutterwave collections, async state handling, polling fallback, payout support | |
| Subscriptions and billing logic | Plans, proration, dunning, failed payment recovery, invoice generation, trial and upgrade paths | |
| Reconciliation and finance reporting | Settlement import, automated ledger diff, exception queue, exportable finance reports |
Why this costs less than a London or New York agency. Our operating costs are lower because of where the work is done, not because the standards are lower. Same Stripe API, same Adyen documentation, same idempotency discipline, same test coverage, same code review. A Western agency doing this work typically charges three to five times more, and most of that gap is their rent and their salaries, not their output.
The other option people weigh is a marketplace freelancer. Cheaper up front, and sometimes genuinely good. The risk is continuity: payment code needs someone reachable when a gateway deprecates an API version or changes a webhook signature scheme. We are still here for the 29 builds we have shipped. If you want the full argument, read freelancer vs agency.
How we work
1. Payments discovery. We ask which countries, which currencies, which rails, whether you need payouts as well as collections, and what your finance team needs to see at month end. Usually one call and a short document. Free.
2. Fixed quote and integration plan. You get the price, the timeline, the gateways, the state machine and the list of edge cases we are handling, in writing. Nothing starts until you approve it.
3. Sandbox build. We build against test credentials first: test cards, declined cards, 3DS challenge cards, sandbox mobile money numbers. You see it working in staging before any real money is involved.
4. Failure testing. We deliberately break things. Duplicate webhooks, delayed callbacks, timeouts mid charge, refunds issued out of band, network drops during confirmation. If it does not survive that, it does not ship.
5. Go live and watch. We switch to live keys, run small real transactions, then monitor the first days of genuine traffic and fix anything the real world surfaces. Ongoing support is available on a monthly retainer if you want us on call.
How to choose a payment gateway developer
Ask these five questions of anyone bidding, including us.
- How do you prevent double charges? If the answer is not idempotency keys within the first sentence, keep looking.
- Where does payment state come from? The right answer is verified webhooks, with the browser redirect treated only as a hint. Anyone relying on the return URL will lose payments.
- What happens if a webhook fails to process? You want to hear about queues, retries, dead letters and manual replay.
- Will card data touch my server? If yes, they should be explaining your PCI obligations unprompted, not waiting for you to raise it.
- Show me a reconciliation report you have built. This separates people who have run payments in production from people who have read the quickstart.
Weigh the gateway choice itself too, not just the developer. Fees, settlement times, chargeback handling and local acquiring differ enormously by market, and the cheapest headline rate is often not the cheapest all in. We will give you a straight comparison for your specific countries. If your payment work sits inside a bigger product, look at fintech software development and custom software development services for how the wider build fits together.
Frequently asked questions
How much do payment gateway integration services cost?
Most projects land , quoted fixed before any work begins, on a 50/25/25 payment plan. The number moves with how many gateways you need, whether mobile money is involved, and whether you want subscription billing or reconciliation reporting on top of one off charges. Discovery and the quote are free.
How long does a payment integration take?
A single gateway with standard checkout, webhooks and refunds is usually two to three weeks. Cards plus mobile money, or multi gateway routing, is typically four to six weeks. Subscription billing with dunning adds time because the failure cases multiply. You get the timeline in the fixed quote, not a vague range.
Can you integrate Stripe and M-Pesa into the same product?
Yes, and this is the work we are asked for most. We build an internal payment interface so your application code does not care which rail it is using, then implement each provider behind it. Card charges are synchronous, mobile money is asynchronous with polling as a fallback, and both land in one unified transaction log so your reporting stays sane.
Will this put my business in PCI scope?
Not if we use hosted fields or a hosted checkout page, which keeps you at SAQ A because card data never reaches your servers. If your business genuinely needs a custom card form, we explain the extra compliance burden before you decide rather than after. Mobile money involves no card data, but we still hold API credentials to a proper standard.
Do you work with clients outside Africa?
Yes. We work with businesses in the US, UK, Europe, the Gulf and Asia. Everything is delivered remotely with a fixed quote, scheduled check ins and code in your own repository. Contact is WhatsApp +256 702946946 and we answer across most time zones. Our advantage is that one team can build the Western gateways and the African rails, which most agencies on either side cannot.