Payment gateway integration
with the edge cases handled.
Stripe, PayPal, Adyen and regional gateways wired in with tax, refunds and edge cases handled.
- — Payment failures arrive as customer complaints, not alerts
- — Finance reconciles gateway payouts by hand each month
- — You are expanding into a market with different payment habits
The work should
change the numbers.
Taking a payment is a two-hour job. Handling a payment properly is a two-week job, and the difference is entirely in the cases nobody demos: the failed webhook, the partial refund, the duplicate submission, the customer whose card is declined for tax-inclusive pricing in a country you had not considered.
We build payment flows that are idempotent, reconcilable and observable. Every transaction has a trail. Every failure has a defined behaviour. Finance can tie the gateway report to the ledger without a spreadsheet.
Because money is involved, this work is tested harder than anything else we ship — including deliberate failure injection before you go anywhere near live keys.
What the engagement
actually contains.
Method and provider selection
Fees, settlement times, regional coverage and payout mechanics compared against your actual order mix.
Checkout implementation
Cards, wallets, bank transfer and buy-now-pay-later wired in with clear error states and retry paths.
Compliance handling
SCA and 3-D Secure, PCI scope minimisation, and tax calculation for the regions you sell into.
Webhook and idempotency design
Duplicate-safe handlers with retries and dead-letter handling so a dropped event never means a lost order.
Refunds, disputes and subscriptions
Partial refunds, chargeback evidence, dunning and renewal logic built rather than improvised.
Reconciliation and reporting
Gateway payouts mapped to orders and to your accounting system, with variance alerting.
- Live payment integration with test coverage
- Webhook handlers with retry and replay tooling
- Refund, dispute and subscription flows
- Tax and compliance configuration
- Reconciliation report or accounting sync
- Runbook for payment incidents
- Payment failures arrive as customer complaints, not alerts
- Finance reconciles gateway payouts by hand each month
- You are expanding into a market with different payment habits
- Subscription renewals fail silently
What usually went wrong
before we were called.
- 01Webhook handlers with no signature verification and no idempotency key
- 02Refunds that update the gateway but never the order record
- 03No defined behaviour when the provider returns a timeout mid-charge
- 04Discovering failed renewals from customer emails rather than alerts
- Payment success rate by method and region
- Involuntary churn on subscriptions
- Manual reconciliation hours per month
- Time to detect a failed webhook
2–4 weeks for a standard integration; 5–8 with subscriptions and tax
What week one
actually looks like.
A written map of every payment path, including refunds, disputes, retries and renewals, plus deliberate failure testing against sandbox keys before anything touches live money.
- Gateway sandbox and live credentials
- Tax and invoicing rules by region
- A finance owner for reconciliation sign-off
- Existing dispute and refund policies
- Negotiating your gateway fees
- Bookkeeping or accounting services
- Chargeback representation
- PCI Level 1 audit services
Scope boundaries stated up front rather than discovered in a change request.
Four stages, visible throughout.
Diagnose
Analytics, search data, sales conversations and a technical audit read together, so the brief is based on evidence rather than opinion.
Structure
Message hierarchy, page architecture and URL plan agreed before design starts — the decisions that are expensive to change later.
Build
A component system engineered by seniors, with technical SEO, accessibility and performance handled as we go rather than bolted on.
Prove
Staged launch, redirect and coverage monitoring, and conversion measured against the baseline we took before starting.
Where this has paid off.
Making expertise easier to access.
A membership platform turned a dense course catalogue into a confident, guided experience.
Hospitality with a human signal.
A rebuilt booking journey and payment integration helped an independent stay win direct reservations.
Payment gateway integration, answered.
For most teams selling in Europe and North America, Stripe is the pragmatic default: excellent APIs, predictable fees, strong subscription tooling. Adyen wins at scale and for complex multi-entity settlement. Regional methods matter more than brand once you sell outside your home market.
We design so that card data never touches your servers — hosted fields or redirect flows keep you in the lightest compliance tier available. We will tell you plainly which SAQ level your setup implies.
Yes, and it is common work. Typical findings are missing idempotency keys, unverified webhook signatures, no retry handling and refunds that update the gateway but not the order record. We audit, prioritise by financial risk, then fix.
E-commerce development
Storefronts built for considered buying: fast catalogues, clean checkout, fewer reasons to leave.
Membership & subscription sites
Gated content, tiers, renewals and billing logic that behaves the same on month twenty-four.
API & third-party integrations
CRMs, ERPs, payments and internal tools connected so the data stops being re-typed by people.
Security hardening & SSL
Hardening, patching, certificates and headers — the unglamorous work that prevents the bad week.
Make payment gateway integration useful.
Bring us the hard thing. We will bring a point of view, a senior team and a clear next step.