Banking Platform Modernisation — Service Decomposition

The Problem

A monolithic banking platform was tightly coupled — one issue took down the entire system. Feature delivery required coordinating across all teams simultaneously, making velocity very slow. The organisation needed a clear map of data ownership before any technical decomposition could safely begin.

My Contribution

I facilitated the service decomposition workshops with each product domain, documenting current-state system dependencies and defining future-state bounded contexts based on data ownership and business capability. I authored BRDs for each of the 12 service domains, managed stakeholder alignment across eight engineering and product teams, and defined the integration acceptance criteria for every service interface. I also led the data migration requirements for each service that required its own data store, ensuring traceability from business requirement to technical implementation throughout the programme.

The Solution

Requirements-led decomposition: current-state dependency mapping, bounded context definition by data ownership, BRDs for all 12 domains, integration contract specifications, cross-team stakeholder alignment, and phased sign-off before any service was independently deployed.

Results

• 99.99% SLA achieved (up from 98%)
• <50ms p99 latency on critical paths
• 10× faster feature deployments
• 12 services with independent deploy cadence
• Scales to 100k+ concurrent users

Tech Stack