What a strong Spring Boot specialist actually knows
Spring Boot is the default for serious Java services, and the difference between a competent and a strong developer shows in the details: transaction boundaries, connection pool sizing, idempotent endpoints and sensible use of Spring Data without hiding slow queries. They know Spring Security well enough to explain a token flow from memory.
Microservice experience matters too. Expect familiarity with Spring Cloud, resilience patterns such as circuit breakers and retries with backoff, and messaging through Kafka or RabbitMQ. Good engineers also say when a modular monolith is the better choice.