Back-end Developer Interview Questions

A back-end web developer is responsible for server-side web application logic as well as the integration of the front-end part. Back-end developers are usually responsible for writing the web services and APIs used by front-end developers and mobile application developers.

Whether you're a job seeker preparing to be interviewed for the role of Back-end Developer or an employer preparing to interview candidates for Back-end Developer position, these Back-end Developer interview questions will help you prepare yourself for the job interview session.

Back-end Developer Interview Questions

Below are a list of some skill-based Back-end Developer interview questions.

1. What is the difference between back-end development and front-end development? How do they interact?
2. What programming languages are you proficient and experienced in?
3. Let's see the projects you've done in the past. Can you show us any?
4. Describe your most challenging programming project. How did you complete it?
5. Do you prefer to work individually or as a team member?
6. Tell us about a time when you improved the efficiency or quality of a program. How did you do it?
7. What are your favorite coding languages? What are the pros and cons of each language?
8. What are your favorite back end development tools?
9. How would you improve the back end of an existing product?
10. What is a RESTful API and how do you use one?
11. When would you use a thread over a process and when would you use a process over a thread?
12. We want to hire someone who can grow into a senior back end developer position. What is your long-term career goal?
13. Describe your process for debugging code.
14. What’s your experience with object-oriented programming (OOP)?
15. What are server response error codes 404 and 500?
16. What is exception handling?
17. What is a design pattern?
18. Tell us about your experience with back-end frameworks
19. Do you have experience working with databases such as MySQL, SQL Server, Oracle etc?
20. What are NoSQL databases? Mention different types of NoSQL databases.
21. Explain SQL injection.
22. Mention some advantages of Web Services.
23. What is the difference between WHERE clause and HAVING clause in SQL?
24. Tell us about your experience developing and maintaining content management systems
25. Do you have experience developing APIs or working with third-party APIs?
26. Tell us about your experience optimizing applications for maximum speed and scalability.
27. Tell us about a time when you received criticism about your work and how you handled it. 
28. Tell me about the largest web application you have ever worked on? What coding were you responsible for?
29. Tell me about your favorite development project to date and what it was like from start to finish.
30. In your opinion, which programming language is the best for back-end development?
31. How would you migrate an application from a database to another, for example from MySQL to PostgreSQL? If you had to manage that project, which issues would you expect to face?
32. In your opinion, is it always needed to use database normalization? When is it advisable to use denormalized databases?
33. How would you find the most expensive queries in an application?
34. What are the general pitfalls of remote procedure calls?
35. How would you programmatically detect file duplicates?

Back-end Developer Interview Questions and Answers

Every interview is different and the questions may vary. However, there are lots of general questions that get asked at every interview.

Below are some common questions you'd expect during Back-end Developer interviews. Click on each question to see how to answer them.

1. What is Your Greatest Weakness?
2. Tell Me About Yourself
3. What is Your Greatest Strength?
4. Are You a Leader or a Follower?
5. Why Do You Want This Job?
6. What Is Your Greatest Accomplishment?
7. What is Your Salary Expectation?
8. Do You Have Any Questions for Us?
9. Why Should We Hire You?
10. Why Do You Want To Leave Your Current Job?