Java: Refresh your understanding of core Java topics such as OOP principles, multi-threading, exception handling, collections, and memory management. Spring Boot: Focus on the essential concepts like dependency injection, annotations, building RESTful APIs, Spring Security (authentication/authorization), JPA/Hibernate for data persistence, and microservices architecture. Frontend (React/JavaScript): Brush up on React hooks, state management, component lifecycle, and integration of REST APIs. Ensure you can handle common React interview questions like optimizing performance, handling forms, and managing global state (e.g., Redux or Context API). Databases: Review SQL for MySQL and NoSQL for MongoDB. Know how to design database schemas, write complex queries, and handle transactions.