Payment Provider Integration for Financial Services Platform

Client Overview

Our client is a rapidly growing European financial services provider offering digital wealth management, investment advisory, and savings products. To expand its service offering and comply with PSD2 requirements, they sought to integrate a robust, scalable payment processing solution that could handle recurring payments, one-time transactions, and payout workflows in multiple currencies.

Project Scope

The goal was to integrate Stripe as a payment provider into their digital platform, ensuring high availability, PCI DSS compliance, fraud prevention measures, and seamless customer experience across web and mobile applications.

Key Objectives:

• Integrate secure one-time and recurring payment flows
  
• Support multi-currency transactions
  
• Enable KYC-compliant payout functionality
  
• Implement strong customer authentication (SCA) for EU users
  
• Achieve full PCI DSS SAQ-A compliance (minimal card data handling)
  

Implementation Details

Architecture and Design

The integration was designed as a modular, microservices-based extension to our customer’s core system, ensuring minimal disruption to existing services. We developed a dedicated Payment Gateway Service that abstracted Stripe APIs and provided a unified internal payment interface.

Key architectural decisions included:

• ‍Server-side integration with Stripe Payment Intents API to manage SCA requirements
  
• Webhook-driven event handling for asynchronous updates (payment success, failure, disputes)
  
• Stripe Connect integration for handling payouts to third-party sellers (investor accounts)
  
• Use of idempotency keys to prevent duplicated transactions during network retries
  
• Vaulting of customer payment methods using Stripe's PCI-compliant infrastructure
  

Technology Stack

• Backend: Node.js with Express framework
  
• Frontend: React web app and React Native mobile app
  
• API Communication: REST with secure OAuth 2.0 token authentication
  
• Database: PostgreSQL for transaction logging and metadata
  
• Infrastructure: Kubernetes (EKS) with CI/CD pipelines
  

Key Integration Components

1. Payment Flows
   
   • One-Time Payments: Implemented using Stripe PaymentIntents API with client-side SDK integration for web and mobile.
     
   • Recurring Payments: Integrated Stripe Subscriptions API with automatic retry logic and failed payment recovery workflows.
     
     
2. Payouts
   
   • Integrated Stripe Connect Custom Accounts to allow them to onboard users programmatically.
     
   • Built automated verification workflows for KYC (Know Your Customer) data collection and validation using Stripe Identity API.
     
     
3. Security & Compliance
   
   • Implemented end-to-end encryption of sensitive customer information.
     
   • All card data tokenized by Stripe – no direct card data touching their servers.
     
   • Implemented mandatory 3D Secure v2 flows for all EEA transactions to comply with PSD2 SCA.
     
   • Regular PCI compliance audits and quarterly penetration testing.
     
     
4. Monitoring & Reliability
   
   • Implemented observability with structured logging (using Elastic Stack) and tracing (using OpenTelemetry).
     
   • Designed retry mechanisms for webhook failures and set up alerting via PagerDuty for payment-related incidents.
     

Challenges and Solutions

1. ‍Challenge: Ensuring low latency payment confirmation for critical investment orders.
   ‍Solution: Pre-create PaymentIntents and use Stripe’s SetupFutureUsage option to reduce the need for customer re-authentication.
   ‍
2. Challenge: Handling asynchronous webhook events reliably.
   Solution: Developed an event deduplication system with message queue buffering (using AWS SQS) to ensure idempotent processing.
   ‍
3. ‍Challenge: Multicurrency reconciliation in financial reporting.
   Solution: Implemented custom exchange rate management to map Stripe settlement reports to internal accounting standards.
   

Results

• Payment processing success rate increased to 99.8% after go-live.
  
• Customer checkout time reduced by 15% through optimized payment flows.
  
• SCA challenge success rate achieved 97%, significantly higher than industry average.
  
• Time-to-market for onboarding third-party sellers reduced by 60%.
  

By integrating Stripe, our customer enhanced its payment capabilities with a highly secure, scalable, and compliant solution. Our engineering team’s deep collaboration with customer’s team ensured that the integration not only met regulatory standards but also positioned the company for future growth in new European and global markets.