Rebuilding a payment system for 2M+ daily transactions
The Problem
NexVault had a 6-year-old monolithic payment processor written in legacy Java. As transaction volume grew 8× over two years, the system became a bottleneck — causing 400ms+ API latencies, frequent timeout incidents, and an on-call team that dreaded Mondays.
Our Solution
We migrated the core transaction engine to an event-driven microservices architecture using Go and Kafka, with a PostgreSQL + Redis hybrid for state management. The migration was done zero-downtime using the strangler fig pattern over 14 weeks.
The Outcome
The new system processes 2.3M transactions per day with a p99 latency of 38ms — a 10× improvement. Infrastructure costs dropped 62% due to more efficient resource utilization. The on-call load reduced by 80%.