Software Engineer interview questions

How the selection process usually works

1. 1

   Online assessment

   Two or three coding problems on a platform like HackerRank, often with MCQs on CS fundamentals and aptitude.

2. 2

   Technical round 1

   Data structures and algorithms on a shared editor or whiteboard. Think aloud.

3. 3

   Technical round 2

   Projects, OOP, DBMS, operating systems and networking. For experienced roles, basic system design.

4. 4

   Managerial / HR

   Behavioural questions, team fit and offer discussion.

Rounds vary between companies. Smaller teams often merge the technical and managerial rounds, while larger companies may add an extra technical round.

Skills to brush up on

• One language in depth (Java, C++, Python or C#)
• Data structures and algorithms
• Object-oriented programming
• DBMS and SQL
• Operating system concepts
• Computer networks basics
• Git
• Debugging and testing

Technical questions

1. 01 What is the difference between an array and a linked list? When would you choose each?

   How to answer: Arrays give O(1) index access and are cache friendly; linked lists give O(1) insert or delete at a known node. Pick based on the access pattern.

2. 02 Explain the four pillars of OOP with an example.

   How to answer: Encapsulation, abstraction, inheritance and polymorphism. Use one running example such as a payment system with different payment methods.

3. 03 How does a hash map work internally, and what happens on a collision?

   How to answer: Hash the key to a bucket index. Collisions are handled by chaining or open addressing. Mention load factor and resizing.

4. 04 What is the difference between a process and a thread?

   How to answer: Processes have separate memory; threads share memory within a process. Threads are cheaper to create but need synchronisation.

5. 05 What is a deadlock, and how can it be prevented?

   How to answer: Name the four Coffman conditions and explain that breaking any one prevents deadlock, for example by always acquiring locks in a fixed order.

6. 06 What are database indexes and what is their downside?

   How to answer: Indexes speed up reads by avoiding full scans, but cost extra storage and slow down inserts and updates.

7. 07 Find the first non-repeating character in a string.

   How to answer: Count characters with a hash map in one pass, then scan again for the first count of one. O(n) time.

8. 08 Reverse a linked list iteratively and recursively.

   How to answer: Iterative: keep prev, current and next pointers. Recursive: reverse the rest, then point next.next back to the current node. Watch the base case.

9. 09 What happens when you type a URL into a browser and press Enter?

   How to answer: DNS lookup, TCP and TLS handshake, HTTP request, server response, then parsing and rendering. Go as deep as the interviewer wants.

Scenario questions

1. 01 Your code works locally but fails in production. How do you debug it?

   How to answer: Check logs and error tracking, compare configuration and environment variables, try to reproduce with production-like data, and narrow down with recent changes.

2. 02 How would you design a URL shortener?

   How to answer: Cover the API, generating unique short codes, the storage choice, redirects and caching popular links. Keep it simple, then scale when asked.

3. 03 You receive a vague requirement from a product manager. What do you do before coding?

   How to answer: Ask clarifying questions, write down assumptions and edge cases, and confirm the expected output before you start.

This guide is written by the JOBSPOT 360 team from common interview patterns for this kind of role. It is not provided by any employer, and real interviews will differ. Read our editorial policy.