Multi-tier library management system deployment with load-balanced web tier, dual application servers (Node.js and Java), PostgreSQL primary-replica database cluster, and Redis caching layer. Traffic flows from web and mobile clients through a WAF-protected Nginx load balancer with SSL termination, then routes to heterogeneous app servers handling REST APIs on ports 3000 and 8080. PostgreSQL primary accepts writes from both app servers and replicates to a standby replica, while Redis cache at :6379 reduces database load and file storage handles book media and backup objects. This architecture demonstrates high availability, horizontal scalability, and separation of concerns across presentation, application, data, and monitoring tiers. Fork and customize this diagram on Diagrams.so to adapt library-specific workflows, add additional app server instances, or integrate external authentication services. The dual-language app server design showcases polyglot microservices patterns suitable for legacy system integration.