Case study 01
Banking & Financial Services
Tier-2 retail bank
- increase in release frequency
- 26× increase in release frequency
- transaction availability sustained
- 99.99% transaction availability sustained
- core system modifications required
- 0 core system modifications required
An API layer that let a 22-year-old core banking system ship monthly
The challenge
Every digital feature required a change to a mainframe-era core with a six-month release cycle. The bank's mobile roadmap was effectively hostage to a system nobody was willing to modify.
What we built
We built an API and event layer in front of the core: read models served from a CQRS projection, writes routed through an idempotent command gateway with compensating transactions, and change-data-capture keeping projections current within seconds.
Architecture summary
CQRS with event-sourced projections · Kafka change-data-capture from the core · API gateway with OAuth 2.0 and mutual TLS · Kubernetes on a hardened private landing zone · full audit trail on every command.
- Java 21
- Spring Boot
- Kafka
- Debezium
- PostgreSQL
- Kong
- Kubernetes
- Terraform
Business impact: Digital feature releases moved from twice a year to fortnightly without a single change to the core system. The core release cycle became irrelevant to the product roadmap.