Rohan Gautam

Java Backend Developer Intern

GEOCO India

Jan 2026 - Jul 2026

Designed and Engineered a modular Java 21 and Spring Boot backend with 60+ REST endpoints covering authentication, product catalog, cart, checkout, orders, payments, support, and admin workflows for an e-commerce platform. Implemented stateless authentication and authorization using Spring Security, JWT, BCrypt, and Google OAuth 2.0, enforcing user-resource ownership checks and role-based access control across USER and ADMIN endpoints. Integrated Razorpay and COD payment workflows using the Strategy pattern, server-side signature verification, and separate order and payment lifecycle states; implemented Redis-backed idempotency to prevent duplicate order and payment processing. Implemented Redis cache-aside caching with configurable TTL, explicit cache eviction, and PostgreSQL fallback for product and category reads, reducing API response times from approximately 250-300 ms to 150-200 ms; added Bucket4j rate limiting for authentication, payments, search, and review endpoints.