The systems I reason about. Spring Boot microservices in production at Capital One — 15+ services behind a gateway router, tuned resource configs, production incidents near zero. Kafka pipelines for event-driven integration across the service mesh.

GraphQL as a data-layer abstraction: the REST-to-GraphQL migration at Publicis Sapient cut over-fetching by roughly 60%. gRPC from the distributed log pipeline built during the UIC MS. Node.js, Bun, and Express on the side of the work that isn't the JVM.

APIs as contracts between systems — the interface is the architecture.