Full Stack Developer Interview Questions

1. What is a full stack developer?

A full stack developer is someone who works on both the frontend and backend parts of a web application.

2. What technologies are used in full stack development?

It includes HTML, CSS, JavaScript for frontend, and Node.js, Java, or Python for backend, along with databases like MySQL or MongoDB.

3. What is the difference between frontend and backend?

Frontend is what the user sees and interacts with, while backend handles the logic, server, and database behind the scenes.

4. What is an API?

An API is a way for the frontend and backend to communicate by sending and receiving data.

5. What is a REST API?

It is an API that uses standard web methods like get, post, put, and delete to access and manage resources.

6. What is the DOM?

The DOM is a representation of the webpage that allows JavaScript to read and change the page content.

7. What is HTML5?

HTML5 is the latest version of HTML and includes new features like support for video, audio, and better form controls.

8. What is the purpose of CSS?

CSS is used to style a webpage, including colors, fonts, spacing, and layout.

9. What is the difference between a class and an id in CSS?

A class can be used for multiple elements, while an id is used for one unique element.

10. What is responsive web design?

It is a design approach that ensures websites look good on all devices like mobiles, tablets, and desktops.

11. What is JavaScript used for?

JavaScript is used to add interactive behavior to websites, such as clicking buttons, animations, and form validation.

12. What is the difference between == and === in JavaScript?

== compares values but not types, while === compares both values and types.

13. What is a promise in JavaScript?

A promise is used to handle tasks that take time, like getting data from a server.

14. What is async/await?

Async and await are used to manage promises and make asynchronous code easier to write and understand.

15. What is a component in React?

A component is a reusable part of a web page that controls its structure and behavior.

16. What is JSX?

JSX is a syntax that lets you write HTML inside JavaScript in React applications.

17. What is the virtual DOM?

It is a lightweight copy of the actual page that helps React update only the parts that change.

18. What is state in React?

State is a place where a component stores information that can change during use.

19. What are props in React?

Props are values passed from one component to another to share data.

20. What are lifecycle methods in React?

These are special functions that run at different times during a component’s life, like when it starts or updates.

21. What is Node.js?

Node.js allows you to run JavaScript on the server side to build backend applications.

22. What is Express.js?

Express.js is a web framework built on Node.js to help create APIs and web applications easily.

23. What is middleware in Express?

Middleware is code that runs before the final request is handled, often used for things like logging or checking user access.

24. What is routing in Express?

Routing is how you define different paths or endpoints in your app and what should happen when each is visited.

25. What is CORS?

CORS is a security feature in browsers that controls how websites can request data from another site.

26. What is the difference between PUT and PATCH?

PUT replaces the entire data, while PATCH updates only certain parts of it.

27. What is the purpose of environment variables?

They store sensitive or changing values like passwords or API keys without hardcoding them in the app.

28. What is JWT?

JWT stands for JSON Web Token and is used to securely transmit user login information between frontend and backend.

29. What is MVC architecture?

It is a design pattern that separates data, user interface, and control logic into different parts of the application.

30. How is async/await useful in backend code?

It helps manage database calls and other time-consuming tasks without blocking the server.

31. What is the difference between SQL and NoSQL databases?

SQL databases use structured tables, while NoSQL databases use flexible formats like documents.

32. What is a primary key?

A primary key is a unique identifier for each record in a table.

33. What is a foreign key?

A foreign key links one table to another by referencing a primary key.

34. What is normalization?

It is a way of organizing data in a database to reduce repetition and improve efficiency.

35. What is indexing in databases?

Indexing speeds up data searches in a database.

36. What is a JOIN in SQL?

JOIN is used to combine rows from two or more tables based on related columns.

37. What is MongoDB?

MongoDB is a NoSQL database that stores data in documents instead of tables.

38. What is the difference between find and findOne in MongoDB?

Find returns many matching records, while findOne returns just the first match.

39. How do you connect MongoDB with Node.js?

By using libraries like Mongoose or the official MongoDB driver.

40. What is Mongoose?

Mongoose is a tool that helps manage data in MongoDB with simpler and structured methods.

41. What is Git?

Git is a version control system that helps track code changes and collaborate with others.

42. What is GitHub?

GitHub is a website where you can store and manage your Git projects online.

43. What is a pull request?

It is a way to ask that your code changes be reviewed and added to the main project.

44. What is Docker?

Docker is a tool that packages your app with all its settings so it runs the same everywhere.

45. What is CI/CD?

CI/CD stands for continuous integration and continuous deployment, which means code is tested and delivered automatically.

46. What is Postman used for?

Postman is a tool used to test APIs by sending requests and checking the results.

47. What are environment variables used for in deployment?

Logging helps you find out what’s happening in your app so you can fix problems.

48. Why is logging important?