Top 100 Web Development Interview Questions
Web development interviews are designed to evaluate a candidate’s understanding of both frontend and backend technologies, as well as their ability to build scalable, secure, and high-performance web applications. These interviews typically cover a wide range of topics including HTML, CSS, JavaScript, modern frontend frameworks, backend concepts, databases, system design, security, and DevOps practices.
Frontend Basics
1. What happens step by step when you enter a URL in a browser and press Enter?
2. What are the roles of HTML, CSS, and JavaScript in a web application?
3. What are the key differences between HTML and HTML5?
4. What is the difference between block-level and inline elements in HTML?
5. What is semantic HTML, and why is it important for SEO and accessibility?
6. What are meta tags, and how do they affect search engines?
7. What is the difference between `class` and `id` attributes in HTML?
8. What is a DOCTYPE declaration, and why is it required?
9. How do HTML forms work, and what are common input types?
10. What is web accessibility, and what are ARIA roles used for?
CSS
11. What is the CSS box model?
12. What is the difference between margin and padding?
13. Explain different CSS `position` values and their use cases.
14. What is the difference between `display: none`, `inline`, `block`, and `inline-block`?
15. What is the difference between Flexbox and CSS Grid? When should you use each?
16. How do you center a div both vertically and horizontally?
17. How does CSS specificity work?
18. What is `z-index`, and how does stacking context work?
19. What are media queries, and how do they help in responsive design?
20. What are CSS preprocessors, and why are they used?
JavaScript – Core Concepts
21. What is the difference between `var`, `let`, and `const`?
22. What is hoisting in JavaScript?
23. What is a closure? Where is it used in real-world applications?
24. What is event bubbling and event capturing?
25. What is the difference between `==` and `===`?
26. What is the difference between arrow functions and regular functions?
27. What are `call`, `apply`, and `bind` methods?
28. What are promises, and how does `async/await` work?
29. What is the difference between `setTimeout` and `setInterval`?
30. What is the difference between debounce and throttle?
Advanced JavaScript
31. What is prototypal inheritance?
32. How does the `this` keyword behave in different contexts?
33. What is the difference between shallow copy and deep copy?
34. How does the JavaScript event loop work?
35. What is the difference between microtasks and macrotasks?
36. What causes memory leaks in JavaScript, and how can they be prevented?
37. What are JavaScript modules and bundlers?
38. What is tree shaking, and why is it important?
39. What are polyfills, and when do you need them?
40. What web storage options are available in browsers?
Frameworks & Libraries (React / Angular / Vue)
41. Why do we use frontend frameworks?
42. What is the Virtual DOM, and how does it improve performance?
43. What are controlled and uncontrolled components?
44. What is the difference between state and props?
45. What are component lifecycle methods or hooks?
46. How does the dependency array in `useEffect` work?
47. When should you use the Context API?
48. How do you optimize frontend performance?
49. What is code splitting, and why is it needed?
50. What is the difference between Server-Side Rendering (SSR) and Client-Side Rendering (CSR)?
Backend Basics
51. What is REST architecture and its principles?
52. What are HTTP methods and common HTTP status codes?
53. What does stateless architecture mean?
54. What is the difference between authentication and authorization?
55. How does JWT-based authentication work?
56. What is the difference between cookies, local storage, and session storage?
57. What is CORS, and how do you resolve CORS issues?
58. What is middleware, and why is it used?
59. Why is API versioning important?
60. What is rate limiting, and how is it implemented?
Database
61. What is the difference between SQL and NoSQL databases?
62. What is database normalization?
63. How does indexing improve database performance?
64. What is the difference between a primary key and a foreign key?
65. What are database transactions and ACID properties?
66. What are joins, and when do you use them?
67. What are the pros and cons of using an ORM?
68. What are common pagination strategies?
69. How do you validate data before storing it?
70. How do you prevent SQL injection attacks?
System Design & Architecture
71. What is MVC architecture?
72. What is the difference between monolithic and microservices architecture?
73. What is an API Gateway?
74. What caching strategies are used in web applications?
75. What is a CDN, and how does it improve performance?
76. What is load balancing?
77. What is the difference between scalability and performance?
78. What is horizontal vs vertical scaling?
79. What is the difference between WebSockets and HTTP?
80. How do you handle file uploads securely?
Security
81. What is XSS, and how do you prevent it?
82. What is CSRF, and how can it be prevented?
83. Why is HTTPS important, and how does TLS work?
84. How should passwords be stored securely?
85. Why should secrets be stored in environment variables?
86. What are secure HTTP headers?
87. What are common OWASP security risks?
88. What is role-based access control (RBAC)?
89. How do you sanitize user input?
90. How do you securely store uploaded files?
DevOps & Practical Knowledge
91. What is the difference between `git merge` and `git rebase`?
92. What is a CI/CD pipeline?
93. Why is Docker used in modern development?
94. What are environment-based builds?
95. How do you handle logging and monitoring?
96. How do you design proper error handling?
97. What tools are used for performance monitoring?
98. How do you debug issues in production?
99. How do you write clean and maintainable code?
100. How do you handle failures and outages in real-world systems?