Be ready to describe the architecture of systems you've worked on, including:
Tech stack: Languages, frameworks, databases, cloud services (e.g., Java, Spring Boot, Redis, Kafka, AWS, etc.).
System design principles: Microservices, monolith, event-driven, etc.
Scalability & performance: How you handled load, caching strategies, and optimizations.
Security: Authentication, authorization, encryption, and data protection.
Reliability & availability: HA (High Availability), failover mechanisms, monitoring/logging (Prometheus, Grafana, ELK, etc.).