Payment integration services that hold up under real customers
My payment integration services cover the parts of payments that tutorials skip: idempotent charges, webhook handling that survives retries and out-of-order delivery, a ledger you can reconcile against the processor, and refunds and disputes that don’t leave your books wrong. Stripe most often, other gateways when the business needs them.
Payments is my deepest specialty. I built the payment platform at Yola, architected the payment integrations for BLU Loyalty, led the architecture at Indiemaker, where subscriptions run on Stripe and sales settle through a third-party escrow provider, and spent seven years writing a book about it.
Where payment integrations actually go wrong
Getting a test card to succeed takes an afternoon. The problems show up months later, with real customers and real money:
- Double charges when a client times out and retries, because the request to the gateway had no idempotency key.
- Missed or duplicated fulfillment because the webhook handler assumed each event arrives exactly once and in order. Stripe delivers at least once and makes no ordering guarantee.
- Subscriptions that drift from what the product thinks the customer is paying for, after upgrades, proration and failed renewals.
- Books that don’t balance. Finance exports the processor’s payout report, it doesn’t match the database, and someone spends days a month in a spreadsheet.
- Refunds and disputes handled by hand in the dashboard, with no record in your own system of what happened or why.
None of these are exotic. They’re the normal failure modes of payment code written once and never revisited.
What I build and fix
- Payment gateway integration – Stripe Payments, Checkout, Payment Intents and Elements, plus other processors and local payment methods where your market needs them.
- Webhook processing with signature verification on the raw body, deduplication on event ID, a queue between receipt and work, and handlers that re-fetch state rather than trusting arrival order. My guide to Stripe webhooks covers the pattern in detail.
- Idempotency end to end: an Idempotency-Key on every mutating call to the gateway, and idempotent endpoints of your own so a double-clicked button does nothing harmful.
- A double-entry ledger inside your product, so balances are derived from immutable entries and every movement of money has an audit trail. See payment reconciliation.
- Subscriptions and usage-based billing – plans, metering, proration, dunning and entitlements. That’s its own page: SaaS billing.
- Marketplace and platform payments on Stripe Connect – onboarding, split payments, holds and payouts. More on that in marketplace payments.
- Migrations between processors or between Stripe integration styles, without breaking live subscriptions.
Why hire a Stripe developer with payments depth
Plenty of developers can wire up Stripe. Fewer have been on the hook when it went wrong in production. At Yola I built the payment platform as the product scaled from 10K to 11M users. At BLU Loyalty I architected the backend and payment integrations for an enterprise loyalty platform with 9 million users. At Indiemaker, a platform for buying and selling side-projects, I led the architecture: subscriptions on Stripe, and sales between buyers and sellers settled through a third-party escrow provider.
I also wrote Payments Playbook, a book about building payment systems that survive real customers. It was seven years in the writing. When I work on your integration, that’s the checklist in my head.
How an engagement runs
- Intro call. You describe the payment flow and what’s hurting. I tell you whether I can help and roughly what the first two weeks would look like.
- Two-week sprint. I review the integration end to end – code, webhook logs, gateway configuration and reconciliation process – and fix the most dangerous problem I find. You get a written list of the rest, ranked.
- Ongoing, if useful. A fixed number of days a week to build out the ledger, billing or Connect work alongside your engineers, with tests and runbooks your team can own.
What I don’t do
I’m a payments engineer, not a compliance firm or a lawyer. I’ll design so that card data never touches your servers, keeping you in the lightest PCI scope your setup allows, and I’ll flag where money transmission, escrow or tax rules probably apply – but you’ll want specialist advice on licensing and regulation. For a broader view of engineering in regulated money businesses, see fintech consulting.
And if you’re a small team with one plan and a hosted checkout, you may not need me at all. Stripe Checkout plus a carefully written webhook handler is the right answer for a lot of companies.
Questions
What do payment integration services include?
Connecting your product to a payment gateway is the start. Good payment integration also covers idempotent API calls, reliable webhook handling, subscription and refund flows, an internal ledger, reconciliation with processor reports, and monitoring so you hear about failures before customers do.
Are you a Stripe consultant only?
Stripe is the processor these pages focus on, including Billing and Connect. The underlying patterns – idempotency, ledgers, reconciliation, webhook processing – apply to any gateway, and I’ll work with whichever processor your market needs.
Can you fix an existing Stripe integration rather than rebuild it?
Usually, yes. Most integrations need targeted fixes: idempotency keys, a proper webhook pipeline, a reconciliation job. A rebuild is rarely necessary, and the two-week sprint is designed to tell you which situation you’re in.
How do you prevent double charges?
Generate an idempotency key per logical payment attempt, store it before calling the gateway, and send it in the Idempotency-Key header so a retried request returns the original result. Pair that with a unique constraint on your own order or payment record.
Worried about what your payment code does under pressure?
Tell me how money flows through your product today. In two weeks I’ll find the riskiest gap and close it.
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