Software Engineer Mock Interview Questions 💻
Practice 80+ curated questions across all rounds to prepare like a pro!
🧍♂️ HR Round (20 Questions)
Q1. Tell me about yourself.
Keep it professional: education, skills, achievements, and why you’re excited for this role.
Q2. What are your strengths and weaknesses?
Pick strengths relevant to the job. For weakness, show how you’re improving it.
Q3. Why do you want to join our company?
Research company goals and culture. Connect them to your career goals.
Q4. Where do you see yourself in 5 years?
Show ambition aligned with company growth and skill development.
Q5. Why should we hire you?
Highlight your relevant skills, enthusiasm, and potential contributions.
Q6. How do you handle stress?
Stay calm, prioritize tasks, and focus on problem-solving.
Q7. Describe a challenge you faced and how you overcame it.
Use the STAR method: Situation, Task, Action, Result.
Q8. What motivates you at work?
Learning opportunities, teamwork, and achieving meaningful goals.
Q9. What are your salary expectations?
Be flexible; mention market range and willingness to negotiate.
Q10. Are you open to relocation?
If yes, express enthusiasm for new opportunities. If not, state valid reasons politely.
Q11. Describe your ideal work environment.
Collaborative, transparent, and growth-oriented.
Q12. How do you handle feedback?
Appreciate constructive criticism and use it to improve.
Q13. What do you know about our company?
Share facts about their products, mission, and recent achievements.
Q14. What are your hobbies?
Share honest hobbies that reflect creativity or discipline.
Q15. Have you ever worked in a team?
Explain a project or group experience, emphasizing communication.
Q16. How do you prioritize tasks?
By urgency, deadlines, and impact on overall goals.
Q17. What kind of work culture do you prefer?
Inclusive, innovative, and collaborative.
Q18. How do you deal with conflicts?
Stay calm, listen actively, and work toward mutual solutions.
Q19. What is your biggest professional achievement?
Describe measurable results from your work or project success.
Q20. Do you have any questions for us?
Ask about team structure, learning opportunities, or company growth.
⚙️ Technical Round (20 Questions)
Q1. What are the four OOP principles?
Encapsulation, Abstraction, Inheritance, Polymorphism.
Q2. What is a REST API?
An architectural style for communication between systems using HTTP methods.
Q3. What’s the difference between GET and POST?
GET retrieves data; POST sends or modifies data on the server.
Q4. What is a database index?
A structure to speed up data retrieval operations on a database table.
Q5. What is normalization?
Process of organizing data to reduce redundancy and improve integrity.
Q6. Explain deadlock in OS.
When two or more processes wait indefinitely for resources held by each other.
Q7. What is polymorphism in Java?
It allows one interface to be used for different underlying data types.
Q8. What’s the difference between a compiler and interpreter?
Compiler translates whole code at once; interpreter executes line by line.
Q9. What is Big O notation?
A mathematical way to describe algorithm time complexity.
Q10. Explain primary vs foreign key.
Primary key uniquely identifies records; foreign key links tables together.
Q11. Difference between process and thread?
Process: independent execution. Thread: lightweight, shares memory.
Q12. What is caching?
Temporary storage of frequently accessed data for faster access.
Q13. Explain version control.
Tracks changes in code, helps collaborate—examples: Git, SVN.
Q14. What is SQL injection?
A security attack inserting malicious SQL code into queries.
Q15. What is an API key?
A unique identifier used to authenticate requests to an API.
Q16. What is a hash function?
Maps data to fixed-size values, used in hashing and encryption.
Q17. What is Docker used for?
Containerization — packaging software with dependencies for consistency.
Q18. What is the difference between HTTP and HTTPS?
HTTPS encrypts communication using SSL/TLS, making it secure.
Q19. What is cloud computing?
Delivery of computing services (servers, databases, storage) via internet.
Q20. What are microservices?
Architectural style dividing an app into small, independent services.
💻 Coding Round (20 Questions)
Q1. Reverse a string in JS.
let s="hello";console.log(s.split('').reverse().join(''));Q2. Check palindrome string.
function isPalindrome(str){return str===str.split('').reverse().join('');}
Q3. Find factorial of n.
function fact(n){return n<=1?1:n*fact(n-1);}
Q4. Find max in array.
console.log(Math.max(...[2,5,1,7]));Q5. Print Fibonacci series.
let a=0,b=1;for(let i=0;i<5 a="" b="" code="" console.log="" i="">Q6. Remove duplicates from array.
let arr=[1,2,2,3];console.log([...new Set(arr)]);
Q7. Count vowels in a string.
let str="hello";console.log(str.match(/[aeiou]/gi).length);
Q8. Sum of array elements.
let arr=[1,2,3];console.log(arr.reduce((a,b)=>a+b));
Q9. Check if number is prime.
function isPrime(n){for(let i=2;i<=n/2;i++){if(n%i===0)return false;}return n>1;}
Q10. Find factorial using loop.
let f=1,n=5;for(let i=1;i<=n;i++){f*=i;}console.log(f);
Q11. Find even numbers in array.
let arr=[1,2,3,4];console.log(arr.filter(x=>x%2===0));
Q12. Find missing number.
let arr=[1,2,4,5];let n=5;
let missing=(n*(n+1))/2 - arr.reduce((a,b)=>a+b);
Q13. Check armstrong number.
function arm(n){let s=n.toString().split('').map(x=>x**3).reduce((a,b)=>a+b);return s===n;}
Q14. Find 2nd largest number.
let arr=[1,4,3,2];arr.sort((a,b)=>b-a);console.log(arr[1]);
Q15. Reverse an array.
let arr=[1,2,3];console.log(arr.reverse());
Q16. Merge two arrays.
let a=[1,2],b=[3,4];console.log(a.concat(b));
Q17. Sort array ascending.
let arr=[5,2,8];console.log(arr.sort((a,b)=>a-b));
Q18. Find GCD of 2 numbers.
function gcd(a,b){return b==0?a:gcd(b,a%b);}
Q19. Find duplicate numbers.
let arr=[1,2,2,3];let dup=arr.filter((v,i,a)=>a.indexOf(v)!=i);console.log(dup);
Q20. Find intersection of arrays.
let a=[1,2,3],b=[2,3,4];console.log(a.filter(x=>b.includes(x)));
🏗️ System Design Round (20 Questions)
Q1. What is system design?
The process of defining architecture, components, and interfaces of a system.
Q2. What is scalability?
The ability of a system to handle increased load by adding resources.
Q3. What’s load balancing?
Distributing incoming traffic across multiple servers.
Q4. What is caching layer?
Stores frequently accessed data to improve performance.
Q5. What is CDN?
Content Delivery Network delivers content from nearest server to reduce latency.
Q6. What’s CAP theorem?
A distributed system can only provide two of Consistency, Availability, Partition Tolerance.
Q7. What’s sharding?
Splitting data into smaller chunks distributed across databases.
Q8. What’s replication?
Copying data across servers to ensure redundancy.
Q9. What’s horizontal scaling?
Adding more machines to handle increased load.
Q10. What’s vertical scaling?
Upgrading existing hardware (RAM, CPU) to handle more load.
Q11. What’s a message queue?
A buffer that holds messages between producer and consumer (e.g., RabbitMQ, Kafka).
Q12. What is rate limiting?
Controlling the number of requests a user can make to prevent abuse.
Q13. Explain database partitioning.
Splitting large tables into smaller, faster pieces for performance.
Q14. What’s eventual consistency?
Data may be inconsistent temporarily but will become consistent eventually.
Q15. What’s a data warehouse?
Centralized storage for structured business data for analysis.
Q16. What is API gateway?
Manages API traffic, authentication, and routing for microservices.
Q17. What’s fault tolerance?
System’s ability to continue working even when components fail.
Q18. What’s a distributed system?
A system whose components are located on networked computers communicating via messages.
Q19. What’s load shedding?
Dropping excess traffic to maintain system stability during overload.
Q20. How do you design a URL shortener?
Use hashing to map long URLs to short codes; store mapping in database.
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