63 Software Engineer Interview Questions and Answers PDF 2025

A Software Engineer is a person who creates computer programs and apps that people use every day. Their job is to design, build, test, and fix software so it works well and solves real problems.

Software Engineers need to know programming languages like Java, Python, or C++, how to write clean code, find and fix errors (called bugs), and work with tools that help build and manage software. They should also understand how computers and networks work.

Preparing for a Software Engineer interview is very important. It helps you explain your skills clearly and answer real job questions confidently. Good preparation also shows that you can solve real problems in the job.

Here, we are sharing popular Software Engineer interview questions and answers for both freshers and experienced people. These include basic topics, advanced skills, and real-world problem questions to help you get ready. You can also download the PDF to study offline anytime

Junior Software Engineer Interview Questions and Answers for Freshers

First, we’ll start with basic questions for entry-level Software Engineer jobs, and then slowly move to tougher and real-life scenario-based questions.

Que 1. What is the difference between a compiler and an interpreter?

A compiler translates the whole program into machine code at once before running it, while an interpreter translates and runs the code line by line.

Que 2. What are variables in programming?

Variables are containers used to store data values like numbers, text, or boolean (true/false). Example in Python:

name = "John"
age = 25

Que 3. What is the difference between a function and a method?

• A function is a block of code that performs a task and can be called anywhere.
• A method is a function that belongs to an object or class.

Que 4. What are loops used for in programming?

Loops help repeat a set of instructions until a condition is met. Examples include for loops and while loops.

Que 5. Explain the difference between if-else and switch statements.

• If-else is used to handle conditions with different possible outcomes.
• Switch is useful when checking a variable against many possible constant values.

Que 6. What is an array?

An array is a data structure that can store multiple values of the same type in a single variable. Example:

fruits = ["apple", "banana", "mango"]

Que 7. What is Object-Oriented Programming (OOP)?

OOP is a programming style that uses objects and classes to design software. It helps organize code better and makes it reusable.

Que 8. Name four principles of OOP.

1. Encapsulation
2. Abstraction
3. Inheritance
4. Polymorphism

Que 9. What is a class and object?

• A class is a blueprint for creating objects.
• An object is an instance of a class.

Example:

class Car:
    def __init__(self, brand):
        self.brand = brand

my_car = Car("Toyota")

Que 10. What is exception handling?

Exception handling is used to catch and handle errors in a program without stopping it. Example:

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero")

Que 11. What are APIs?

APIs (Application Programming Interfaces) allow two software systems to talk to each other and share data.

Que 12. What is version control? Give an example.

Version control is used to track and manage changes in code. Example: Git.

Que 13. What is the difference between GET and POST methods in APIs?

• GET is used to fetch data from a server.
• POST is used to send data to a server.

Que 14. What is SQL used for?

SQL (Structured Query Language) is used to store, manage, and retrieve data from databases using commands like SELECT, INSERT, and DELETE.

Que 15. What is responsive web design?

Responsive web design ensures that a website looks good and works well on all screen sizes, like phones, tablets, and computers.

Que 16. Explain the difference between frontend and backend development.

• Frontend: What users see and interact with (HTML, CSS, JavaScript).
• Backend: Behind-the-scenes work like databases, servers, and APIs (Python, Java, Node.js).

Que 17. What is REST API?

REST API (Representational State Transfer) is a set of rules used to build APIs that allow communication between systems over HTTP.

Que 18. What are unit tests?

Unit tests are small tests written to check if a particular part (unit) of the code works correctly.

Que 19. What is multithreading?

Multithreading allows a program to run multiple tasks at the same time, helping improve performance.

Que 20. What is continuous integration (CI)?

Continuous Integration is a process where code changes are automatically tested and merged into a shared codebase regularly, helping detect issues early. Tools like Jenkins and GitHub Actions are commonly used for CI.

Also Check: Python Interview Questions and Answers

Senior Software Engineer Interview Questions and Answers for Experienced

Que 21. What is the difference between concurrency and parallelism?

Concurrency means handling multiple tasks at the same time, but not necessarily running them together. Parallelism means running multiple tasks truly at the same time, usually on multiple cores.

Que 22. What is SOLID in software engineering?

SOLID is a set of five principles to write clean and maintainable code:

• S: Single Responsibility Principle
• O: Open/Closed Principle
• L: Liskov Substitution Principle
• I: Interface Segregation Principle
• D: Dependency Inversion Principle

Que 23. What is the difference between microservices and monolithic architecture?

• Monolithic architecture means all features are built into one single app.
• Microservices split features into small, independent services that can work alone and talk through APIs.

Que 24. How do you handle memory leaks in an application?

By using tools like profilers to find unnecessary memory usage, releasing unused objects, following good coding practices, and running garbage collection properly.

Que 25. What is load balancing?

Load balancing distributes incoming network traffic across multiple servers to ensure no single server gets overloaded, improving performance and availability.

Que 26. What is a design pattern? Name a few.

A design pattern is a common solution to recurring software problems. Examples:

• Singleton
• Factory
• Observer
• Strategy

Que 27. What is the CAP theorem?

CAP stands for:

• Consistency: All nodes see the same data.
• Availability: Every request gets a response.
• Partition Tolerance: System works even if parts of the network fail.
  According to the theorem, only two of the three can be fully achieved at the same time.

Que 28. Explain CI/CD pipelines.

CI/CD stands for Continuous Integration and Continuous Deployment. It’s a process where code changes are automatically built, tested, and deployed to production using automated pipelines.

Que 29. How do you manage database migrations in production?

By using version control for database scripts, automated deployment tools, proper backups before migration, and testing changes in staging environments before live deployment.

Que 30. What are stateless and stateful applications?

• Stateless applications do not store session information between requests.
• Stateful applications remember previous interactions and store session data.

Que 31. What are middleware in web applications?

Middleware are software layers that sit between client requests and server responses, handling tasks like authentication, logging, or routing requests.

Que 32. How do you ensure code quality in a team project?

Using:

• Code reviews
• Unit tests and integration tests
• Linting and static code analysis
• Following coding standards
• CI/CD pipelines for automatic checks

Que 33. How does OAuth 2.0 work?

OAuth 2.0 allows third-party apps to access user data without sharing passwords. Users grant permission through a token-based system that controls access.

Que 34. What is the difference between horizontal and vertical scaling?

• Horizontal scaling adds more servers to handle increased load.
• Vertical scaling increases resources (CPU, RAM) of the existing server.

Que 35. What is dependency injection?

Dependency injection is a design pattern where an object gets its dependencies from outside rather than creating them itself, making code easier to manage and test.

Que 36. What is containerization? Give an example.

Containerization packages software code and dependencies together to run consistently across environments. Example: Docker.

Que 37. Explain graceful degradation and progressive enhancement.

• Graceful degradation: App still works with limited features when something fails.
• Progressive enhancement: App starts with a basic version and adds advanced features where possible.

Que 38. How do you handle large file uploads in web applications?

By using chunked uploads, streaming data, setting file size limits, and storing files outside the main app server (like cloud storage).

Que 39. What are WebSockets?

WebSockets provide a way for two-way communication between client and server over a single, long-lived connection, useful for real-time applications like chat or live updates.

Que 40. How do you improve application performance?

• Optimizing database queries
• Using caching (like Redis)
• Code optimization and refactoring
• Load balancing
• Reducing API calls
• Asynchronous processing and multithreading

Software Engineer Technical Interview Questions and Answers

Here we have some technical questions and answers for software engineers.

Que 41. What is the difference between stack and queue?

A stack follows Last In, First Out (LIFO) order – the last item added is the first to be removed.
A queue follows First In, First Out (FIFO) order – the first item added is the first to be removed.

Que 42. What is recursion in programming?

Recursion is when a function calls itself to solve smaller parts of a problem until a stopping condition (base case) is reached.

Example:

def factorial(n):
    if n == 1:
        return 1
    else:
        return n * factorial(n-1)

Que 43. Explain the difference between abstract class and interface.

• An abstract class can have method definitions and abstract methods (without code).
• An interface only contains method declarations (no code), and a class must implement them.

Que 44. What is Big O notation?

Big O notation describes the performance or complexity of an algorithm, especially how it scales as input size grows.
Example: O(n), O(n²), O(log n)

Que 45. What is multithreading, and why is it useful?

Multithreading allows a program to run multiple tasks at the same time, improving speed and performance, especially in applications that handle many requests simultaneously.

Que 46. What is garbage collection in programming?

Garbage collection automatically removes unused or unreferenced objects from memory, helping free up space and prevent memory leaks.

Que 47. Explain JOIN in SQL and name its types.

JOIN in SQL is used to combine rows from two or more tables based on a related column.
Types of JOIN:

• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• FULL JOIN

Que 48. What is RESTful API?

A RESTful API follows REST rules and allows communication between systems using HTTP methods like GET, POST, PUT, DELETE, and supports stateless communication.

Que 49. What is unit testing? Why is it important?

Unit testing is the process of testing small parts (units) of code to ensure they work correctly. It helps catch bugs early and ensures that changes in code don’t break existing functionality.

Que 50. What is the purpose of indexing in a database?

Indexing helps speed up data retrieval from a database by creating quick lookup references, reducing the time needed to search large datasets.

Also Check: Technical Interview Questions and Answers

Java Software Engineer Interview Questions and Answers

Que 51. What is the difference between JDK, JRE, and JVM?

• JDK (Java Development Kit): A software package to develop Java applications.
• JRE (Java Runtime Environment): Allows running Java programs but not developing them.
• JVM (Java Virtual Machine): Runs Java bytecode and makes Java platform-independent.

Que 52. What are access modifiers in Java?

Access modifiers control the visibility of classes, methods, and variables.
Types:

• public: Accessible everywhere
• private: Accessible within the class only
• protected: Accessible within the same package or subclasses
• default (no modifier): Accessible within the package

Que 53. What is method overloading and method overriding?

• Method overloading: Defining multiple methods in a class with the same name but different parameters.
• Method overriding: A subclass provides a specific implementation of a method already defined in its parent class.

Que 54. What is the difference between == and equals() method in Java?

• == compares object references (whether they point to the same memory location).
• equals() compares actual values or contents of two objects.

Que 55. What is exception handling in Java?

Exception handling is managing errors using try-catch blocks to prevent program crashes. Example:

try {
    int result = 10 / 0;
} catch (ArithmeticException e) {
    System.out.println("Cannot divide by zero.");
}

Que 56. What is the difference between ArrayList and LinkedList in Java?

• ArrayList: Stores elements in continuous memory, fast for reading, slow for inserting/deleting in the middle.
• LinkedList: Elements are linked via nodes, good for inserting/deleting but slower in accessing elements directly.

Que 57. What is multithreading in Java?

Multithreading allows multiple parts of a Java program to run at the same time, improving performance, especially in applications with many tasks running together.
Implemented using Thread class or Runnable interface.

Also Check: Java interview Questions and Answers

Embedded Software Engineer Interview Questions and Answers

Que 58. What is embedded software?

Embedded software is the programming code written to control devices like washing machines, cars, medical devices, and more. It runs on microcontrollers or processors inside hardware.

Que 59. What is the difference between microcontroller and microprocessor?

• Microcontroller: A small computer on a single chip that has processor, memory, and input/output built-in, used in simple devices.
• Microprocessor: Just the processor; needs external memory and peripherals, used in computers and advanced systems.

Que 60. What is real-time operating system (RTOS)?

An RTOS is an operating system designed to respond quickly and manage tasks in real-time, ensuring critical tasks are completed on time.

Que 61. Why is memory management important in embedded systems?

Because embedded devices often have limited memory, managing memory carefully helps avoid crashes, slowdowns, and ensures the device works smoothly.

Que 62. What is interrupt in embedded systems?

An interrupt is a signal that temporarily stops the main program so the system can respond to an important event (like button press), and then returns to continue the program.

Que 63. What languages are commonly used in embedded programming?

Mostly C and C++ are used, as they give low-level hardware control and high performance. Sometimes assembly language is used for very specific hardware tasks.

Software Engineer Interview Questions PDF

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FAQs: Software Engineer Interview Questions

Conclusion

We have included software engineering interview questions with answers, covering roles from junior to senior levels. We have also shared technical and scenario-based questions. We have also provided a PDF file of questions for easy preparation at any time. Good luck with your next interview.