50 Must-Know Java Backend Interview Questions (Free)

Preparing for a Java backend interview and not sure what to revise first? This free checklist gives you 50 must-know questions that come up again and again in backend interviews.

What's inside (50 questions):

• REST API & Spring Web (5)

• Streams & Collections (3)

• Core Java Collections (2)

• Core Java & JVM Internals (5)

• Spring Data JPA & Hibernate (5)

• Spring @Transactional (5)

• Concurrency & Threading (5)

• Microservices Architecture (5)

• Kafka & Messaging (5)

• Kubernetes (3)

• AWS (2)

• SQL & Database (3)

• Production Issues & Debugging (2)

How to use it:

1. First pass: mark your strong, medium, and weak topics.
2. Second pass: practise answering each question aloud in 2–3 minutes.
3. Final pass: focus on production scenarios, trade-offs, and debugging.

Please note: this is a question-only edition. Answers are not included. Use it as a checklist, a mock-interview bank, or a daily revision plan.

Many of the questions are explained visually in my short videos. Follow Interview Prep Hub for more.

Want the full set? The Java Backend Interview Question Bank has 516 questions across 21 topics.

Format: PDF, 7 pages. For personal interview preparation use.