Senior Backend Engineer for Pachoo, a high-traffic food delivery platform. Responsible for the core application logic, database architecture, and API ecosystem. Core Tech: Java 17, Spring Boot, Spring Security, PostgreSQL. API Design: Architected and documented RESTful APIs to handle complex user flows, real-time order states, and third-party payment integrations. Database Management: Designed the relational schema in PostgreSQL; optimized complex queries and indexing to maintain high performance during peak order volumes. Business Logic: Implemented the "engine" of the platform, ensuring data consistency across order placement, driver assignment, and transaction history. Collaboration: Worked closely with frontend and mobile developers to ensure seamless API integration and with the DevOps team to facilitate smooth application deployment.