Engineered the core reimbursement and claims engine for a multi-tenant enterprise US healthcare benefits platform processing participant claims across FSA, HRA, and HSA plan offerings.
The legacy monolithic codebase suffered from concurrency exceptions under high load, tightly-coupled business logic leaking across service boundaries, and unvalidated multi-tenant database access.
Refactored legacy claims processing workflows into modern ASP.NET Core microservices with clean architecture. Implemented tenant-isolated query filters in Entity Framework Core, optimized parallel LINQ and EF queries using thread-safe context factories, resolved N+1 query bottlenecks, and redesigned high-throughput SQL indexing strategies. Profiled under synthetic load using Apache JMeter to validate zero concurrency failure rates.
Successfully processed 4,061 requests with zero HTTP or thread concurrency failures during a 600 RPM peak load test. Replaced legacy stored procedures with performant EF Core queries, reduced database roundtrips, and established domain-driven design bounded contexts across 4 core claims processing services.