📌 Common Backend Interview Questions

Below are categorized questions that frequently appear in backend developer interviews.

1. System Design

• How would you design a URL shortener?
• How to design a rate limiter?
• What are the differences between monolith and microservices?
• What is a message queue and when would you use one?

2. Databases

• What is the difference between SQL and NoSQL?
• How does indexing work in PostgreSQL?
• What is ACID and why is it important?
• How do you scale a relational database?

3. API Design

• What’s the difference between REST and GraphQL?
• How do you handle versioning in APIs?
• What are idempotent HTTP methods?
• How to secure an API?

4. Caching & Performance

• What is the role of Redis in a web application?
• How would you prevent cache stampede?
• What is a CDN and when should you use one?

5. Deployment & DevOps

• What is a container and how does Docker work?
• What are health checks in a production service?
• How would you set up CI/CD for a microservices architecture?