Solution
Payment Gateway Integration
Safe payment processor integration with idempotent webhooks, tokenized card data and reconciliation that catches mismatches early.
NDA on request · Free, no-obligation estimate · Reply within one business day
Charging a card is the easy part. Incidents come from a webhook arriving twice and charging someone twice, a payment succeeding while the order fails to save, or processor payout figures that differ from your own ledger at month end. Most payment integration work goes into handling those failure paths correctly, and the happy path takes little effort by comparison.
We integrate processors including Stripe, Braintree, Adyen, and PayPal into existing products, whether that is a one-time checkout flow, a marketplace splitting payouts between multiple parties, or a platform adding payments to a product that did not have them before.
Scope
Core features
Hosted or embedded checkout
A hosted checkout page or an embedded form using the processor's own client-side components, so card details go directly to the processor and never touch your servers.
Idempotent webhook processing
Every webhook handler is built to safely process the same event twice, since payment processors resend webhooks on any delivery uncertainty and a handler that is not idempotent will double-apply the result.
Refunds and partial refunds
Full and partial refunds route through the same processor relationship and get reflected in your own order and ledger records automatically, not as a manual follow-up step.
Multi-currency and multi-method support
Cards, digital wallets, and bank transfers across multiple currencies get supported through the processor's existing rails, rather than building separate payment logic per method.
3D Secure and SCA compliance
Strong Customer Authentication gets triggered for card payments where required, particularly for European transactions under PSD2, without adding unnecessary friction for payments that do not need it.
Fraud detection and risk rules
Processor-native risk scoring gets combined with rules specific to your business, such as flagging unusual order sizes or velocity, rather than relying on the processor's generic defaults alone.
Reconciliation against processor payouts
Automated reconciliation compares what the processor pays out against what your internal ledger expects, surfacing mismatches before they reach a monthly close instead of after.
Tokenization to reduce PCI DSS scope
Card data is tokenized by the processor and never stored on your servers, which keeps most integrations eligible for the lightest PCI DSS self-assessment questionnaire rather than a full audit.
Architecture
Choices that shape the build
Idempotency keys to prevent double charges
Every charge request carries an idempotency key, so a retried request from a flaky network connection reuses the original charge result instead of creating a second one.
Webhook signature verification
Every incoming webhook gets verified against the processor's signature before being trusted, which stops a forged request from triggering a fake payment confirmation.
Handling a payment that succeeds when the order does not
The system needs a defined recovery path for the case where a charge succeeds but the follow-up order creation fails, since leaving that unhandled results in a customer who paid for nothing.
Reconciliation between the processor and your books
Payout timing, processor fees, and currency conversion all affect what actually lands in your bank account relative to what was charged, and reconciliation needs to account for all three, not just the charge amount.
PCI DSS scope through tokenization
Keeping raw card numbers off your servers by using the processor's tokenized fields is what keeps most businesses eligible for the simpler PCI DSS self-assessment rather than a full-scope audit.
Redundancy for high transaction volume
Businesses processing a high volume of payments sometimes integrate a second processor as a fallback, which adds complexity but protects revenue if the primary processor has an outage.
Build vs buy
When to build and when to buy
Stripe Checkout, Payment Links, and similar hosted flows from Braintree or Adyen are the right call when you want to accept payments with the least engineering effort and the lightest PCI DSS scope, since the processor hosts the entire payment form. We recommend starting there unless the checkout experience needs to be deeply embedded in your own UI.
A custom integration using the processor's client-side components, such as Stripe Elements, is worth the extra build effort when checkout needs to match your product's design closely or needs logic a hosted page cannot express, such as splitting a payment across multiple recipients in a marketplace. A fully custom, self-hosted payment form that directly touches card data is rarely justified given how much PCI scope tokenized fields avoid.
Delivery
How delivery is phased
Define payment flows and compliance scope
We map every payment scenario the product needs, one-time charges, refunds, and any split payments, and confirm the PCI DSS scope the chosen integration approach will fall under.
Integrate the gateway and webhooks
Checkout, refund, and webhook handling get built and tested against the processor's sandbox environment, with idempotency and signature verification in place from the start.
Build reconciliation and failure handling
Reconciliation against payouts and recovery logic for partial failures, like a successful charge with a failed order, get built and tested before moving to real transactions.
Test with real transactions and launch
A limited live period with real, small transactions validates the full flow before it opens to all customers. This typically takes a few weeks from integration start to full launch.
Technology
Stack we usually choose
FAQ
Questions about Payment Gateway Integration
How do you prevent double-charging a customer with payment webhooks?
Every charge uses an idempotency key and every webhook handler is built to process the same event safely more than once, so a network retry or a duplicate webhook delivery from the processor cannot result in two charges for one purchase.
What is PCI DSS scope and how does tokenization reduce it?
PCI DSS scope refers to which of your systems fall under card data security requirements. Tokenizing card details through the processor's own client-side fields means raw card numbers never reach your servers, which typically keeps you eligible for the simplest self-assessment questionnaire instead of a full audit.
Should we use Stripe Checkout or build a custom payment form?
Stripe Checkout or a similar hosted flow is faster to launch and keeps PCI scope minimal, and is the right default. Build a custom form using Stripe Elements when the checkout experience needs to match your product's design closely or needs logic a hosted page cannot support, such as a marketplace split payment.
How do you handle a payment that succeeds but the order fails to create?
The integration includes a defined recovery path, such as a background job that retries order creation against a confirmed charge, or an automatic refund if the order genuinely cannot be created, so a customer is never left having paid for something that was never fulfilled.
Can a payment integration support multiple currencies and payment methods?
Yes. Processors like Stripe and Adyen support cards, digital wallets, and local payment methods across many currencies through the same integration, so adding a new supported currency or method is usually a configuration change rather than new development.
Services
Services this draws on
- API DevelopmentWe design, build, document and version REST and GraphQL APIs so partners can integrate without asking your engineers for help.
- Backend DevelopmentWe build the server-side systems beneath your product, including data models, business logic, queues and the infrastructure that keeps them fast under load.
- E-commerce DevelopmentShopify and WooCommerce storefronts, headless commerce front ends and custom checkout flows, all shaped to your catalog, pricing and fulfillment setup.
- Custom Software DevelopmentWe build software around the processes your business already runs on, so operations no longer depend on spreadsheets, workarounds and tools never built for your workflow.
Industries
Industries that commission this
- Retail & E-commerceInventory, POS and storefront software that stays synchronized across every channel, with EDI connected for your wholesale partners.
- Fintech & BankingFinancial software with KYC/AML checks and PCI DSS-aligned payment flows designed in from the schema onward, with ledgers that reconcile to the cent.
- Travel & HospitalityBooking engines, channel managers and guest apps that keep rate and inventory data consistent across your PMS, OTAs and GDS connections.
- Professional ServicesEngagement management, time tracking and client portals designed around how consulting and advisory firms bill for their time.
Insights
Further reading
- 6 min readWhat Custom CRM Development Cost Looks LikeCustom CRM development cost starts near $40,000 for a focused pipeline tool and reaches $250,000+ for a multi-team platform with automation and reporting.
- 7 min readCustom Development vs No-Code ComparedCustom development vs no-code tools, compared on build speed, cost at scale, and where each approach holds up as your workflows grow more complex.
- 8 min readWhat Custom Software Development CostsCustom software development cost runs from $15,000 for a simple internal tool to $500,000 or more for enterprise platforms. This guide covers what drives it.
Discuss your payment gateway integration project
Send a short description of the project. A senior engineer reads each request and answers with questions, next steps and an early budget range.