Banking Platform Modernization
Regional commercial bank — monolith decomposition to microservices
Challenge
A regional bank had operated on a monolithic core banking platform for twelve years. The platform served all product lines through a shared relational schema with no service boundaries. Test coverage was negligible — engineers were reluctant to change anything for fear of side effects that wouldn't be detected until production. Release cycles averaged four weeks, requiring coordination across the entire engineering organisation for each deployment. The bank had new digital products waiting to launch that the monolith could not support without significant rework.
Approach
AlgoDomain used a strangler fig migration pattern — identifying domain boundaries within the monolith and replacing them incrementally with separate Java microservices deployed on Kubernetes. An API gateway was introduced as the first step to route traffic and enable the parallel running of old and new components during transition. Each new service was built with comprehensive automated test coverage. Data migration used dual-write patterns to maintain consistency while cutover occurred.
Outcome
The programme ran across six phases over 26 months. By the end of phase three, the first three product domains were running on independent services with daily deployments — the first time in the bank's history that releases could happen independently per domain. At programme completion, the monolith was fully decommissioned. Release cycle time dropped from four weeks to daily. System availability in production reached 99.97% over the subsequent 12-month measurement period.
4w → daily
Release cycle time
99.97%
Production availability
0 → 87%
Automated test coverage
26 mo.
Programme duration