Building & Scaling a Fault-Tolerant BNPL Payment Platform

Brand: Not Disclosed

Industry: Fintech

Technologies: Erlang, Cowboy, DynamoDB, Kafka, Terraform, Datadog, Jenkins, AWS, Splunk, Docker

Partnership: 2019 - Present

Overview

Our client is a leading Swedish fintech company providing “Buy Now, Pay Later” (BNPL) services for online storefronts. The platform allows customers to pay in installments or at a later date and offers additional services like credit assessments, fraud prevention, and account management. As one of the largest BNPL providers in Europe, the company has recently expanded into the US and other international markets.

We partnered closely with the client to enhance scalability, fault tolerance, and reliability across multiple regions, ensuring seamless payment processing and secure operations for millions of users.

The Challenge

The client’s core payment gateway processes millions of transactions daily, leaving zero room for downtime. They required a partner capable of:

Enhancing scalability and fault tolerance
Supporting real-time processing and analytics
Integrating multiple payment providers efficiently
Maintaining secure, reliable global infrastructure
Managing proactive monitoring, on-call support, and automated scaling

Ensuring uninterrupted service while expanding into new markets was a critical business priority.

The Solution

Our engineering team co-created a robust, distributed BNPL platform leveraging Erlang’s fault-tolerant architecture. Key solutions included:

Fault-Tolerant Architecture: Optimized Erlang systems for high concurrency and zero downtime
Global Infrastructure: Managed across Europe, North America, and Australia
RESTful API Integrations: Connected with 5+ payment processors, including Stripe, Checkout.com, Adyen, Worldpay, and Ebanx
Secure Protocols & Card Tokenization: Ensured safe payments with card art support and PCI-compliant security
Real-Time Analytics: Kafka-based event streaming for monitoring, reporting, and automated bookkeeping
Integration of Mastercard Click-to-Pay: Streamlined European transactions
Proactive Monitoring & Support: Continuous monitoring, on-call support, and scaling before peak periods

We collaborated closely under a flat, transparent structure to ensure rapid decision-making, high responsiveness, and continuous improvement.

Tech Stack

Business Impact

The enhanced BNPL platform delivered significant outcomes:

Seamless processing of up to 3.2 million transactions per region per day with zero downtime
End-to-end integration with 5+ payment processors across Europe, North America, and Australia
Faster transaction processing via Erlang’s concurrent architecture
Automated settlement reports and event generation for accurate financial reconciliation
Secure and user-friendly payments with card tokenization and card art support
Integration of Mastercard Click-to-Pay for European markets