American Signature Inc

At American Signature, I worked primarily on payment and warehouse management systems. On the payment side, I implemented complete payment lifecycle processes including authorization, settlement, refunds, and re-authorizations, integrated with external payment gateways for fraud and card validation, and optimized rebill processing for over 150K orders using delay queues. On the warehouse side, I developed services supporting inventory management, receiving, picking, packing, and shipment workflows while ensuring inventory consistency through locking mechanisms. The application was built using Spring Boot microservices, Hibernate/JPA, Eureka, Feign, and centralized configuration management.

If I were starting the project again, I would focus earlier on event-driven architecture, distributed tracing, reusable retry frameworks, proactive performance testing, and stronger automated integration testing with payment gateways. These changes would reduce operational overhead and improve scalability as transaction volumes grow.