During February 2025, Puppsupr developed robust Fulfillment Inbound API validation and credential interfaces for the amzn/selling-partner-api-samples repository. Focusing on backend development with Java and AWS, they implemented comprehensive input validation across fulfillment inbound API operations, consolidating validation scaffolding to ensure reliable data contracts for partner integrations. Their work introduced enum classes to define API response keys, enhancing consistency in API interactions, and established an interface for secure credential provisioning. This feature addressed reliability and security requirements, laying the groundwork for scalable credential management. The depth of the implementation reflects a strong understanding of API integration and secure backend architecture.