Monolith to Microservices: Migrating a Java Spring Boot Platform

Meridian Financial Services ran its entire lending and account-servicing platform as one large Java monolith. A single deploy meant rebuilding and releasing the whole application, so a one-line fix to the notifications module carried the same risk and rollback blast radius as a core ledger change. Release cycles had slowed to once every few weeks because no team was willing to own the risk of shipping faster, and a memory leak in any one module could take the entire platform down.

They needed to break the monolith apart without a risky big-bang rewrite — migrating module by module, keeping the platform live and compliant with financial-services uptime requirements throughout.

WebSool ran a domain-driven decomposition of the monolith, identifying bounded contexts — accounts, payments, notifications, reporting — and extracting them one at a time into independently deployable Spring Boot services behind a strangler-fig pattern, so the monolith kept serving traffic for routes not yet migrated. Each extracted service got its own datastore and API contract, communicating through an event-driven backbone built on Kafka instead of direct database coupling.

We containerized every service with Docker and deployed them on Kubernetes with independent CI/CD pipelines, so a change to the notifications service could ship in minutes without touching the core ledger. Centralized distributed tracing and structured logging gave the engineering team visibility across service boundaries that the monolith's application logs never provided.

Deployment time for a typical change dropped 90%, from a multi-week release train to same-day, service-scoped deploys, with zero customer-facing downtime throughout the migration. Individual service failures no longer cascade into full platform outages, and Meridian's engineering teams now own and release their services independently instead of coordinating a single monolithic release train.