31 Common Back-End Developer Interview Questions

The following are some of the most common questions asked to back-end developers during interviews:

1. How would you describe yourself as a developer?
2. Tell me about a project that you have worked on recently. What was the goal, and how did you accomplish it?
3. What is an object model?
4. How would you implement a simple user authentication system?
5. What is the difference between polymorphism and inheritance?
6. What is the difference between serialization and deserialization?
7. What is the difference between concurrency and parallelism, and what are some examples of both?
8. Explain how to cache a database query, and when it makes sense to do so.
9. What is a database?
10. What are the main functions of a database?
11. How do you create a database in SQL?
12. What is the difference between MySQL and PostgreSQL?
13. How do you connect to a database from PHP?
14. What are some of the tools you use for back-end development?
15. What are your favorite technologies?
16. What is your opinion on the coding style?
17. How do you feel about code reuse?
18. How do you handle errors in your code?
19. What's the best way to handle a bug report?
20. What is your favorite programming language? Why?
21. What is your favorite feature of your favorite programming language?
22. What are some pros and cons of your favorite programming language?
23. How would you design an API for an e-commerce website if it had to support both mobile and desktop applications written in Javascript, HTML5, and CSS3?
24. What do you know about our product?
25. What would you say is the most challenging part of this job?
26. What's the biggest mistake you've made in the past, and how did you handle it?
27. How does a project get from idea to finished product?
28. What's your favorite thing about working for [company name]?
29. What is your biggest weakness?
30. What are the most important skills that a back-end developer should have?
31. Why should we hire you instead of someone else?