FinFlow — Cloud-Native Payment Infrastructure

The challenge

FinFlow’s on-premise payment infrastructure was running on hardware that was 6 years old, hitting capacity limits, and requiring 18-hour maintenance windows for upgrades. They were PCI-DSS Level 1 compliant — any cloud migration had to maintain that certification.

Our approach

Phase 1: Architecture design (6 weeks)

We ran a series of workshops to document every component of the existing system, then designed a target-state architecture on AWS that:

• Kept all payment data in a single AWS region (eu-west-1) for GDPR compliance
• Used separate VPCs for cardholder data environments (CDE) with strict network segmentation
• Replaced the batch processing model with event-driven streaming via Kafka

Phase 2: Infrastructure as Code (8 weeks)

We wrote the entire infrastructure in Terraform — 12,000 lines across 40 modules. Everything is version-controlled, code-reviewed, and deployed through CI.

Key components:

• EKS clusters — Kubernetes for all stateless services, with node autoscaling
• Aurora PostgreSQL — multi-AZ for the primary transaction database
• Kafka (MSK) — event streaming for payment events, audit logs, notifications
• Vault — secrets management and dynamic credentials for all services

Phase 3: Migration (10 weeks)

We migrated using a blue-green strategy: new infrastructure ran in parallel with production until we had proven 2 weeks of zero-incident operation. Cutover took 4 minutes.

Results

The new infrastructure processes the same load at 60% of the cost, deploys 40× more frequently, and has had zero unplanned downtime since launch.