Production-grade Weather API platform demonstrating enterprise-level backend engineering practices through deliberate over-engineering for learning and portfolio credibility. Core Engineering Implementations: • Layered Architecture: Clean separation across controller, service, and provider layers enabling independent evolution, testability, and provider replaceability without touching routes • Redis-Based Caching: TTL-based caching strategy (5-min window) with cache key normalization, dramatically reducing external API calls while ensuring data freshness • Distributed Rate Limiting: Redis-backed throttling (10 req/60s per API key) providing distributed-safe state management across multiple instances • Graceful Degradation: Fail-open architecture where Redis failures bypass cache and rate limiting without causing downtime, mirroring production resilience patterns • API Key Authentication: Lightweight service-to-service authentication enabling per-consumer rate limiting and access control • Provider Abstraction Layer: Normalized external API integration (OpenWeatherMap) preventing vendor lock-in and enabling seamless provider switching • Centralized Error Handling: Consistent error responses with proper HTTP status codes and no internal detail leakage Request Lifecycle: Authentication → Rate Limiting → Cache Layer → External Provider → Normalized Response This architecture mirrors real-world backend systems used in production, not toy demos—demonstrating scalability, testability, and professional code organization principles. Stack: Node.js, Express.js, Redis, OpenWeatherMap API, RESTful design patterns