From Legacy to Leading Edge: Modernizing a Full-Suite Online Payments Platform

The product is a digital payments platform offering the full array of services for e-commerce: card acquiring, online payment processing, smart POS integration, near-instant card payouts, etc.

Designed in mind with maximum flexibility and security, the solution supports over 150 currencies and real-time settlements in major denominations, offering a complete spectrum of service for startups, fledgling companies, and enterprises.

The client contacted us to lead modernization of their legacy systems and enhancing core platform functionality. Their goal was to deliver seamless online and in-store payments, scale effortlessly, and ensure airtight security for a rapidly growing user base.

6 Backend Engineers (.NET specialists)

3 Frontend Developers (Angular 8)

2 DevOps Engineers

1 Solution Architect

1 QA Engineer

1 Project Manager

As the client scaled across Europe, their legacy infrastructure began to show its age. What once supported a handful of merchants now needed to serve thousands, securely, seamlessly, and globally. The ambition was clear: to evolve from a functional payment processor into a modern, multi-channel fintech platform without disrupting ongoing operations.

The path forward was complex. We had to balance innovation with stability, flexibility with compliance, and performance with robust security. Key challenges included:

• Modernizing fragmented legacy architecture while maintaining business continuity
• Enabling multi-channel payment support: online, in-app, in-store, and via link
• Integrating with Visa/Mastercard for near-instant payouts
• Achieving compliance with PCI-DSS and other security protocols
• Optimizing for high-speed performance under increasing transaction loads
• Implementing end-to-end encryption and MFA without sacrificing UX

Backend: .NET

Frontend: Angular 8

Database: PostgreSQL

Security: Auth0, Keycloak, TLS 1.3, AES-256, OpenSSL

AI Features: Python-based models with scikit-learn, TensorFlow

Deployment: Flask REST endpoints

DevOps: GitLab CI/CD, Docker, Kubernetes

To address these challenges head-on, we designed a comprehensive modernization strategy focused on scalability, interoperability, and user trust. Here’s how we brought the new platform to life, one module by one towards customer recognition.

Online Payments

A customizable Payment Gateway is designed for maximum merchant flexibility and reach. It was built to integrate seamlessly across diverse e-commerce environments, providing provides comprehensive support for:

• Hosted Payment Pages: They grant secure, PCI-compliant checkout experience that can be quickly embedded by merchants.
• Direct API Integration: For businesses requiring deeper customization or specialized workflows, a robust and well-documented API enabled direct, flexible integration into their existing systems.

Card Payouts

Enabled fast payouts to 80+ countries using Visa Direct and Mastercard Send, including Pay by Link options achieved through:

• Visa Direct and Mastercard Send Integration: Direct integration with these leading global networks facilitated near-instant transfers, crucial for gig economy payouts, marketplace settlements, and quick refunds.
• Inclusive Pay by Link Options: Extending the flexibility of payouts, we’ve incorporated “Pay by Link” functionality, allowing payments to be initiated and received via simple links shared through digital channels.

Acquiring

Delivered secure acquiring services across 150+ currencies with real-time fraud alerts, pre-auth capture, and next-day settlement support, supported by real-time AI-powered fraud alerts. Thanks to the advanced machine learning models (MLM), the system provides immediate alerts on suspicious transactions, significantly reducing fraud incidents and chargebacks.

Subscription Billing and In-App Payments

To support recurring revenue models, a sophisticated recurring billing logic was built directly into the platform. It automates the entire subscription lifecycle, significantly enhancing revenue predictability and reducing manual administrative effort.

Furthermore, added SDK support for in-app payment collection enabled seamless and secure transactions directly within mobile applications. This was a critical step for modernizing the platform’s reach.