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Top Full Stack Developer Interview Questions and Answers

Nowadays, full-stack developers are in high demand in the fast-paced technology industry. These professionals can work on both front-end and back-end development. They are an important part of any programming team. Their duties include making websites that are functional and easy to use.

This blog post will discuss what you need to become a full-stack developer. We will focus on the kind of skills required for a given role as well as provide comprehensive sets of interview questions with answers for beginners and experienced developers. If you have an upcoming job interview or just want to boost your knowledge of full-stack development, then go through our guide!

Who is a Full Stack Developer?

A full-stack developer is a versatile IT professional who works on both sides of web development: front-end & back-end. They can perform various tasks such as user interface design, database management, and server-side operations, among others. This means they have the capacity to make everything about software development a success by ensuring it works well enough, has fast performance rates, and looks attractive.

These specialists employ different techniques plus frameworks when finishing final products which users can interact with. Take an example of someone conversant with developing top-most responsive pages like HTML5, CSS3, and JavaScript, including processing form response at the backend and storing response into the database too.

Skills and Responsibilities of the Full Stack Developer

Key Skills

• HTML, CSS & JavaScript: Skills required in developing static pages using HTML scripting languages like (core) CSS & JS frameworks also called libraries.
• Backend Programming Languages: A brief idea about Node.js, Python, Java or Ruby may be helpful when working on them at server side level.
• Database Management: This field involves managing structured SQL servers such as MySQL or NoSQL like MongoDB or Hadoop DBMS named PostgreSQL.
• Version Control: Using services like Git (GitHub) helps monitor code adjustments effectively.
• API Development and Integration: Building RESTful services & APIs.
• Responsive Design: The capacity to create websites that can work on different devices as well as screen sizes.
• Problem-Solving: Strong analytical skills to identify and fix bugs or optimise code.
• DevOps Knowledge: Understanding of deployment processes, CI/CD pipelines, and cloud services.

Key Responsibilities

• Designing and Developing: Creating both front-end and server-side code for web applications.
• Database Management: Doing database operations yourself but still guaranteeing data integrity.
• Testing & Debugging: Efficiently detecting program source code flaws & correcting them.
• Collaboration: Working with other developers, stakeholders and designers to achieve project objectives.

Full Stack Developer Interview Questions and Answers For Freshers

1.   Explain the differences between Agile and Waterfall methodologies.

2.   What do you understand about CORS (Cross-Origin Resource Sharing)?

CORS (Cross-Origin Resource Sharing) is a security feature implemented by web browsers that allows or restricts resources (like fonts, scripts, or data) on a web page from being requested from another domain. It’s a way to control access to resources on a server from a different origin. For instance, if a webpage on domain-a.com wants to fetch data from domain-b.com, CORS headers determine whether the request should be allowed or blocked.

3.   Difference between <div> and <span> Tag in HTML

Both <div> and <span> are HTML elements used for grouping and styling content, but they serve different purposes.

4.   Tell me about an Iframe in HTML.

An Iframe (Inline Frame) in HTML is an element that lets you put another HTML document inside the current page. This could be advertisements, videos or other websites which are added as small sections in your webpage for example.

Example:

5.   What is the difference between properties and attributes in HTML?

6.   What is multithreading, and how is it used?

Multithreading allows for the simultaneous execution of multiple threads within a single process. It is useful when undertaking tasks like parallel processing, handling multiple tasks simultaneously and running background tasks without affecting the performance of the main thread.

Example in Python:

7.   What is an application server?

An Application Server is software that provides an environment for running web applications. It handles the business logic, manages database connections, and serves dynamic content to users. Examples include Apache Tomcat, Microsoft IIS, and JBoss.

8.   What are the types of design patterns?

9.   What are the popular full-stack technologies?

10. How does SDLC work?

SDLC (Software Development Life Cycle) is a structured process for developing software, ensuring high quality and meeting user requirements. It involves the following stages:

• Planning: Defining goals, scope, and resources.
• Analysis: Gathering and analysing user requirements.
• Design: Creating system architecture and design specifications.
• Implementation: Writing and developing the software.
• Testing: Validating that the software meets requirements.
• Deployment: Releasing the software to users.
• Maintenance: Ongoing support, updates, and bug fixes.

11. Explain the differences between TypeScript and JavaScript.

12. What are the key features of MongoDB?

MongoDB is a NoSQL database known for its flexibility and scalability. Key features include:

• Document-Oriented: Stores data in JSON-like documents.
• Schema-Less: Allows dynamic changes in the data structure without a predefined schema.
• Horizontal Scalability: Scales easily across multiple servers.
• Indexing: Supports various types of indexing to improve query performance.
• Aggregation Framework: Provides tools for data analysis and transformation.

13. What is CSS?

CSS (Cascading Style Sheets) is a language used to describe the presentation of a web page. It controls the layout, colours, fonts, and overall visual appearance of HTML elements. CSS allows developers to create consistent and visually appealing web pages that work across different devices and screen sizes.

14. What is the CSS Clear property?

The CSS Clear Property is used to control the behaviour of floating elements. It specifies whether an element should be moved down below floating elements that precede it, ensuring that it does not overlap or wrap around the floated elements.

Example:

15. What are the differences between RGB vs RGBA colour format?

16. What’s your favourite coding language? why?

My favourite coding language is Python. It’s versatile, easy to read, and has a vast range of libraries that make it suitable for tasks ranging from web development to data science. Python’s simplicity and readability make it an excellent choice for both beginners and experienced developers. Its large community and extensive documentation further enhance its usability.

17.  Explain the difference between GraphQL and REST (Representational State Transfer)

18. Describe the difference between thread and process.

19. How would you optimise an existing website for a new client?

Optimising an existing website involves several steps:

• Performance analysis: Use tools like Google PageSpeed Insights to identify performance bottlenecks.
• Image optimization: Compress and resize images for faster loading.
• Minify code: Minify CSS, JavaScript, and HTML files to reduce file size.
• Enable caching: Implement browser and server-side caching to improve load times.
• Optimise database queries: Review and optimise database queries to reduce load times.
• Improve SEO: Update meta tags, keywords, and content structure for better search engine ranking.
• Mobile optimization: Ensure the website is fully responsive and mobile-friendly.
• Security enhancements: Implement security best practices, such as HTTPS and regular updates.

20. Explain the differences between React and Angular.

21. Outline steps involved in continuous integration.

Continuous integration (CI) typically consists of several steps that ensure code quality and smooth integration:

• Version control: Developers commit code to a shared repository, usually a Git branch.
• Automated testing: Every commit triggers automated tests that confirm that the code works as expected.
• Build process: Code is automatically built for compilation error checking and artefact generation purposes.
• Code review: Other developers may also take part in reviewing while some automation tools may verify their quality assurance state.
• Merge: After passing tests and review, the code is merged into the main branch.
• Deployment: Often with automation this includes publishing of the new code to a staging or production environment.

22.  What is the difference between GET and POST methods?

23. How would you find a memory leak?

To find a memory leak, follow these steps:

• Monitor memory usage: Use tools like Task Manager, top, or Activity Monitor to observe memory usage over time.
• Profile the application: Use profiling tools like Valgrind, VisualVM, or Chrome DevTools to identify memory usage patterns.
• Check for unreleased resources: Look for objects, files, or resources that are not properly released after use.
• Use garbage collection logs: In languages with garbage collection (e.g., Java), check logs to see if objects are not being collected.
• Isolate the problem: Comment out or disable sections of code to narrow down the source of the leak.
• Fix and test: After identifying the leak, fix it and run tests to ensure the issue is resolved.

24. Explain the differences between SQL JOIN types (INNER JOIN vs OUTER JOIN).

25. How comfortable are you with design patterns?

I am quite comfortable with design patterns. I have experience implementing various design patterns, such as Singleton, Factory, Observer, and MVC, in different projects. I understand when to use each pattern and how they contribute to code reusability, maintainability, and flexibility.

25. What factors are necessary for successful integration?

Successful integration requires careful planning and attention to several key factors:

• Clear requirements: Ensure that all stakeholders have a clear understanding of the integration goals.
• Compatibility: Verify that the systems, technologies, and APIs involved are compatible.
• Testing: Conduct thorough testing in a controlled environment before full deployment.
• Documentation: Maintain comprehensive documentation to guide the integration process.
• Communication: Keep open lines of communication between teams to address issues promptly.
• Security: Implement security best practices to protect data during and after integration.
• Scalability: Plan for future growth to ensure that the integration can handle increased demand.

26. Explain the differences between HTTP and HTTPS.

27. Do you prefer AMD or CommonJS? Why?

I prefer CommonJS for server-side JavaScript, particularly with Node.js, because it’s widely supported and follows a synchronous loading model, which is straightforward and easier to debug. AMD is more suitable for browser-based development due to its asynchronous loading, which can improve performance in the browser environment. The choice depends on the environment and specific use case, but CommonJS is more commonly used in server-side development.

28. Explain the differences between Monolithic and Microservices architectures.

29. What are the strategies to optimise a website to be as efficient and scalable?

To optimise a website for efficiency and scalability, consider the following strategies:

1. Code optimization: Minify CSS, JavaScript, and HTML to reduce file sizes.
2. Image optimization: Compress images and use modern formats like WebP.
3. Caching: Implement browser and server-side caching to reduce load times.
4. Content Delivery Network (CDN): Use a CDN to serve content from the nearest server to the user.
5. Database optimization: Optimise queries, use indexing, and consider database caching.
6. Load balancing: Distribute traffic across multiple servers to avoid overloading a single server.
7. Asynchronous loading: Load JavaScript and other resources asynchronously to prevent blocking the rendering of the page.

30. What’s the difference between Normalisation and Denormalization?

31. What is the Flask web framework?

Flask, a Python lightweight web framework, helps developers build web apps quickly. It is simple to use and has fewer built-in features offering flexibility. Flask adheres to the standard of WSGI (Web Server Gateway Interface) and comes with basic tools such as routing, request handling, and templating which makes it ideal for small to medium projects or for developers who like picking their own libraries.

32. What is ReactJS?

ReactJS is a library in JavaScript created by Facebook for creating user interfaces, specifically single-page applications. This means that it allows developers to create reusable UI components, thus making it easier to manage the view layer of an application. React applies virtual DOM so that it can efficiently update and render components resulting in better performance in dynamic web applications.

33. Explain the differences between Git Merge and Git Rebase.

34. What is Next JS?

Next.js, a React framework, enables server-side rendering and static site generation for React apps. It provides routing capabilities, automatic code splitting, server-side rendering features etc., thus reducing development time. Use Next JS to build high-performance SEO-friendly web apps.

35. Explain the differences between MVC and MVVM architecture.

36. What is Django?

Django is a high-level Python-based web framework that promotes quick development as well as clean pragmatic design principles. This framework employs the Model-View-Template (MVT) architectural pattern and has in-built facilities such as user authentication, database interactions and URL routing among others. It scales well, and guarantees the safety of your systems while still being fully documented.

37. What is MySQL?

MySQL is an open-source Relational Database Management System (RDBMS) that uses Structured Query Language (SQL) for data management purposes. It is widely used in web applications where data needs to be stored or retrieved because it supports features like transactions, indexing and replication. This popularity lies in its reliability, scalability and simplicity hence ideal for both small-scale and large-scale applications.

38. Difference between List and Array in Python

39. Explain the difference between structured and unstructured databases.

40. What is the event loop in Node.js?

The event loop on Node.js handles asynchronous operations on this platform. To manage non-blocking I/O operations on Node.js’ single-threaded approach, the event loop comes to use. It keeps checking the call stack and callback queue and then executes callbacks when the former is empty to ensure efficient execution of asynchronous code.

41. Is GraphQL faster than REST?

In certain scenarios, particularly those with complex queries requiring multiple REST API calls, GraphQL can be faster compared to REST API. Clients in GraphQL can request specific data they require which may reduce how much data is being transferred and how many network requests are made. Performance varies depending on implementation details, query complexity, and how the server handles those queries. For simple single-resource requests, rest can be simpler and faster.

42. What are the differences between Server-side Scripting and Client-side Scripting?

43. Explain the differences between SQL and NoSQL databases.

44. What is the ‘use strict’ mode in JavaScript?

‘use strict’ is a directive in JavaScript that enables strict mode, which helps catch common coding errors and ‘unsafe’ actions, such as assigning values to undeclared variables. It makes debugging easier and helps avoid potentially problematic JavaScript features.

Example:

Using strict mode is recommended as it promotes better coding practices and can prevent subtle bugs.

45. Explain the differences between synchronous and asynchronous programming.

46. Explain the differences between Docker and Virtual Machines (VMs).

Full Stack Developer Interview Questions and Answers For Experienced

47. State the difference between <div> and <span> Tag in HTML.

48. What is the difference between PUT and PATCH methods?

49. What is the difference between the ‘resetting’ and ‘normalising’ CSS?

• Resetting: Removes all default browser styling. This provides a clean slate but requires more customization.
• Normalising: Preserves useful default styles and improves cross-browser consistency. It’s a more balanced approach.

50. What Factors Do You Need for Successful Integration?

• Clear Requirements: All stakeholders should understand the integration goals.
• Compatibility: Ensure that systems and APIs are compatible.
• Thorough Testing: Conduct testing to catch issues early.
• Good Communication: Maintain open lines between teams.
• Security: Implement best practices to protect data.
• Scalability: Plan for future growth to handle increased demand.

51. What Are the Advantages of Using Unit Tests?

• Early Bug Detection: Catches issues during development.
• Refactoring Safety: Ensures that changes don’t break existing functionality.
• Documentation: Serves as documentation for expected behaviour.
• Code Quality: Encourages better design and modular code.
• Confidence: Provides confidence to developers that their code works as intended.

52. Explain the differences between OAuth and JWT for authentication.

53. When would you clear floats in CSS?

Clearing floats is necessary when you want to ensure that elements after a floated element do not wrap around it. This is often needed after using floating elements for layout purposes to prevent issues with layout or overlapping content.

Example:

54. Explain how you’d share code between files.

• Module Export/Import: In JavaScript, use export to expose functions or variables and import to bring them into another file.
• Common Libraries: In Python, create reusable modules and import them as needed.
• Inheritance: In object-oriented languages, use inheritance to share common logic across classes in different files.
• Packages: Organise code into packages or namespaces to logically group shared code.

55. Explain the differences between RESTful API and SOAP API.

56. What are the advantages of using unit tests?

• Early Bug Detection: Helps identify issues during development.
• Code Documentation: Unit tests serve as documentation for expected behaviour.
• Confidence in Refactoring: Ensures that changes do not break existing functionality.
• Continuous Integration: Allows automated testing in CI/CD pipelines.
• Improved Design: Encourages writing modular, testable code.

57. Explain how you’d reduce the loading time for a website

• Minimise HTTP Requests: Reduce the number of files needed to load the page.
• Optimise Images: Compress images and use modern formats like WebP.
• Leverage Browser Caching: Cache static resources to avoid repeated requests.
• Minify CSS and JavaScript: Remove unnecessary characters and whitespace.
• Use a CDN: Distribute content across geographically dispersed servers.
• Lazy Load Assets: Load images and scripts only when needed.

58. What is it referred to as when you are talking about ACID with respect to database systems?

ACID is the abbreviation of Atomicity, Consistency, Isolation and Durability. These four qualities make certain that database transactions take place in a smooth way.

• Atomicity: It implies that every operation must complete within a transaction; otherwise all operations will be rolled back.
• Consistency: Ensures that after completion of a transaction, the database moves from one valid state to another.
• Isolation: Makes sure that individual transactions do not interfere with each other.
• Durability: Assures a system failure would not undo the committed transactions.

59. Explain the differences between static and dynamic typing in programming languages.

60. What is an application server?

An application server refers to a software framework that provides an environment for running web applications. It manages business logic, database connections and client-server communications. Examples include Apache Tomcat, Microsoft IIS and JBoss.

61. What is referential transparency?

Referential transparency describes the property of functions where their output will always be consistent given the same input without depending on any external state or side effects. This is very important in functional programming as it leads to a more predictable and maintainable code base.

62. What are the types of design patterns?

• Creational Patterns: Deal with object creation mechanisms (e.g., Singleton, Factory Method).
• Structural Patterns: Handle the composition of classes or objects (e.g., Adapter, Composite).
• Behavioural Patterns: Manage object interaction and responsibilities (e.g., Observer, Strategy).

63. What are the differences between an abstract class and an interface class?

64. What is docstring in Python?

A docstring is a string literal used to document a Python module, class, function, or method. It is placed right after the definition and can be accessed using the __doc__ attribute.

Example:

65. What is Entity Bean?

Entity Bean is a type of Enterprise JavaBean (EJB) that represents persistent data stored in a database. Each instance of an Entity Bean corresponds to a row in a database table, and the bean’s state is synchronised with the database.

66. What is an Iterator?

An Iterator is an object that allows traversal of elements in a collection (like lists or arrays) one at a time. In Python, an iterator must implement the __iter__() and __next__() methods.

Example:

67. Explain the differences between Continuous Integration (CI) and Continuous Deployment (CD).

68. What is dependency injection?

Dependency injection is a design pattern where an object’s dependencies are provided externally rather than the object creating them itself. This promotes loose coupling and easier testing.

69. What is continuous integration?

Continuous integration (CI) is a development practice where developers frequently integrate code into a shared repository. Each integration is verified by an automated build and testing process to detect issues early.

70. What is a Bootstrap grid system?

The Bootstrap grid system is a layout system that uses a series of containers, rows, and columns to arrange content. It’s based on a 12-column grid, allowing responsive layout designs that adjust across different screen sizes.

71. Explain the differences between XML and JSON

72. How to add the badge to the list group in Bootstrap?

To add a badge to a list group item in Bootstrap:

73. Explain long polling.

Long polling is a technique where the client requests information from the server, and the server holds the request open until new data is available, reducing the need for frequent polling. This helps simulate real-time updates.

74. How to use calc() in Tailwind CSS?

Use calc() in Tailwind CSS by applying it directly in your custom CSS or inline styles, as Tailwind does not have a built-in utility for calc():

75. What is an Alert component in Bootstrap?

The Alert component in Bootstrap is used to display important messages to the user. It comes with various contextual styles (e.g., success, danger, warning) and can be dismissible.

76. What are some of the uses of Docker?

• Containerization: Encapsulates applications and their dependencies in lightweight containers.
• Development Environment: Provides consistent environments across different stages of development.
• Continuous Integration/Deployment: Facilitates CI/CD pipelines by allowing automated builds and tests in isolated environments.
• Microservices: Deploys and manages microservices architectures efficiently.

77. Explain the differences between HTTP/1.1 and HTTP/2

78. Explain the ‘this’ keyword in JavaScript.

The ‘this’ keyword in JavaScript refers to the object from which the function was called. Its value depends on the context in which it is used (e.g., global, object, or function context).

Example:

79. What is callback hell?

Callback hell refers to the situation where multiple nested callbacks make the code hard to read and maintain. This often occurs in asynchronous programming when each callback depends on the previous one, leading to deeply nested structures. Using promises or async/await can help mitigate this issue.

80. Explain the differences between Encryption and Hashing

Preparing for a full-stack developer interview requires a solid understanding of both front-end and back-end technologies. By mastering the key concepts, tools, and techniques discussed in this blog, you’ll be well-equipped to answer even the most challenging questions. From understanding the nuances of various programming languages to knowing the intricacies of web development frameworks, being prepared will set you apart from other candidates.

As you continue your journey in full-stack development, remember that the industry is always evolving. Staying up-to-date with the latest trends and continuously practising your skills will not only help you in interviews but also in your overall career growth. Keep learning, stay curious, and embrace the challenges ahead.