Top Full Stack Developer Interview Questions (2024)

Table of Contents

What is it like to go into the interview process for a Full-Stack Developer role? It is quite common to feel anxious at first, especially if this is your first time on the hot seat. One of the most popular and hottest professions in the tech industry is a Full Stack Development role. Full-stack developers do not only specialize in front-end and back-end development but are also experts with a wide range of skill sets and knowledge. Its high level of responsibility makes it one of the most important careers in tech and companies are willing to pay handsomely for those with the right skillset and diverse knowledge. Likewise, if you’re thinking about a career in Full Stack Development, the future is yours. The InterviewBit team has put together a list of 30+ full stack developer interview questions and answers that will help you prepare for this role. These questions have been hand-picked based on what you will likely encounter in the interview.

Full Stack Developer Interview Questions for Freshers

1. To develop a project from scratch, what technologies and languages would you need or what skills a full stack developer should have?

A full-stack developer must be familiar with the following:

Programming Languages: Full-stack developers should be competent in more than one programming language, such as Java, Python, PHP, Ruby, C++, etc.
Front End technologies: You should be familiar with front-end technologies such as HTML5, CSS3, JavaScript, etc. Knowledge of third-party libraries such as jQuery, Ajax, Angular, ReactJS, etc., is also important.
Frameworks: This requires proficiency in a variety of development frameworks, including Spring, Spring Boot, Django, MyBatis, PHP, Hibernate, and others.
Databases and caches: As a full stack developer, you should also know about various DBMS (Database Management Systems) technologies like MySQL, SQLite, Oracle, and MongoDB. It is helpful to have a basic understanding of caching mechanisms like redis, memcached, varnish.
Design Ability: Having a good understanding of design is also important if you wish to become a successful Full-Stack web developer. Moreover, the person should be aware of the principles of prototyping and UX/UI design.
Server: Experience with Apache or NGINX would be beneficial. Good knowledge of Linux helps enormously when administering servers.

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2. Which language is the most preferred by full-stack developers?

Full Stack Developers utilize several programming languages. Ideally, a candidate should be fluent in several languages, preferably some for designing the front end and others for fixing the back end. Since Full Stack developers work with a variety of technologies and applications, they must be proficient in at least two to three of the most popular languages such as Java, Python, Ruby, PHP, C++, etc.

3. Explain Pair Programming.

In pair programming, two programmers share only one machine and work together. During the development process, one programmer will be the driver who codes and another will act as the observer (navigator) who will make sure the code is written correctly, proofread and spell-check it, while also deciding where to go next. Roles can be swapped at any time: the driver becomes the observer and vice versa. You can also call it “pairing”, “paired programming”, or “programming in pairs”.

5. What is Callback Hell?

Callback Hell, or Pyramid of Doom, is a common anti-pattern seen in asynchronous programming code (multiple functions running at the same time). This slang term describes a large number of nested “if” statements or functions. In simple terms, Callback hell is a situation where you have multiple asynchronous functions. Those functions depend on one another, so it could get quite messy with so many callback functions nested in so many layers. The use of callback functions leaves you with code that is difficult to read and maintain, and looks like a pyramid as shown below:This also makes it more difficult to identify the flow of the application, which is the main obstacle to debugging, which is the reason for the famous name of this problem: Callback Hell.

6. Explain Long Polling.

Long polling is defined as a web application development technique used to push information/data from servers to clients as quickly as possible. When a request is made from the client to the server, long-polling maintains the connection between the two. This connection is maintained until the information is ready to be sent from the server to the client. Once a server receives a request from a client, the connection does not close immediately; the connection is only closed once the server has sent the data back to the client or when a timeout threshold has been reached (connection timeout).

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7. Can you tell me what are the latest trends in Full Stack Development? Also, how do you keep yourself updated about the new trends in the industry?

Each business needs emerging technology to thrive, whether it is mobile or web application development. This is why they hire front-end developers, back-end developers, or full-stack developers depending on their technology needs. According to industry experts, candidates who are passionate about full-stack development should be aware of these trends:

The rise in frameworks and libraries like ReacJs and VueJs, progressive apps, real-time web apps, and mobile web development.
Enhancements to JavaScript are beneficial to programming
The emergence of a more compatible extension.

The interviewer may ask you how you keep updated with new trends in the industry. You can explain how you gain your knowledge and understanding by learning from friends, colleagues, or online. That’s an appropriate way of answering the question. This is a good time to show off any personal projects you have undertaken that apply your skills. Also, you might mention the webinars or forums that you attend regularly.

8. State difference between GraphQL and REST (Representational State Transfer).

For decades, REST (Representational State Transfer) has been a popular architectural way to design APIs (Application Programming Interfaces), but the popularity of GraphQL over the past few years threatens to topple REST. In general, REST and GraphQL both aim to transfer data over internet protocols including HTTP.

GraphQL	REST
It is a Query Language for APIs that enables declarative data fetching to provide clients control over which data to retrieve from the API.	It is an API design architectural style that defines a set of constraints to create web services.
GraphQL is known for its high predictability. With this, you can send requests to your API and get the exact results you are looking for without having to include anything you don’t need. GraphQL queries give predictable results, which improves their usability significantly.	On the other hand, REST’s behaviour depends on the HTTP and URI methods used. API consumers can therefore be unsure of what to expect when calling an endpoint.
API security can be ensured by GraphQL, though the security features aren’t as mature as those of REST. GraphQL, for instance, assists in integrating data validation, but users are left to figure out how to apply authentication and authorization measures.	API security can be enforced in several ways using REST. You can implement multiple methods of API authentication, such as HTTP authentication, to ensure REST API security.
With GraphQL, you can retrieve everything you need through a single API request. You can specify the structure of the information you need, and the server will return the same structure to you, so there is no need to over-and under-fetch.	Consequently, since REST APIs have rigid data structures that return the specified data whenever they are accessed, you may end up with unwanted data or have to make multiple requests before getting the right data. As a result, the server’s response time (to return information) can be prolonged due to these shortcomings.
It only supports JSON format.	XML, YAML, JSON, HTML, and other formats are supported, as well.
The main use cases of GraphQL are mobile applications and multiple microservices.	Rest is mainly used for simple applications and resource-driven applications.

9. What is CI (Continuous Integration)?

CI (Continuous Integration), as its name implies, is the process of automating and integrating code changes into a single software project, often several times a day. The purpose of this DevOps practice is to enable developers to merge their code changes into a central repository where automated tests and builds can run. Automated tools are used to assert the new code’s correctness before integration. A source code version control system is the crux of the CI process. The version control system is also supplemented with other checks like automated code quality tests, syntax style review tools, and more.

Advantages:

Integrating regularly has the main benefit of detecting errors quickly and more easily. Since most changes introduced are small, pinpointing the specific change that caused a defect is easy.
As a result of the smaller code changes and easier fault isolations, CI reduces MTTR (Mean Time to Resolution).

10. Explain the meaning of multithreading.

The thread is an independent part or unit of a process (or an application) that is being executed. Whenever multiple threads execute in a process at the same time, we call this “multithreading”. You can think of it as a way for an application to multitask.

11. Explain the benefits and drawbacks of using “use strict”.

In ECMAScript5, a new feature known as strict mode allows you to run a program or function within a strict operating context. Certain actions, therefore, cannot be taken due to this strict context, and more exceptions are thrown. When the “use strict” statement is used, the browser is instructed to use “strict” mode, which is a more restricted and safer JavaScript feature set. You can specify “use strict” at the top of a function to evaluate the JS in strict mode. In strict mode, more errors are thrown and some features are disabled to make your code more robust, clear, and accurate.

12. What are some of the uses of Docker?

One of the thorniest problems in software development is dealing with the different environments across different machines and platforms. Using Docker, you can isolate your applications from your infrastructure, which is crucial to delivering software quickly. Developers can package and run their applications into containers, executable components that have all the OS (Operating System) libraries and dependencies needed to run the application in any environment. It does not matter what is installed on the host—containers are lightweight and include everything needed to run applications.

The code has to pass through many different environments as it travels from the developer’s machine to production. Consequently, each of these environments may be slightly different. Using Docker streamlines code development and deployment, as it provides a consistent environment from development to production.
Docker’s primary purpose is to simplify configuration. With VM (Virtual Machine), you can run any platform with its configuration on top of your infrastructure. Docker offers the same functionality without the overhead of virtual machines.

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13. Explain event loop in Node.js.

The event loop in JavaScript enables asynchronous programming. With JS, every operation takes place on a single thread, but through smart data structures, we can create the illusion of multi-threading. With the Event Loop, any async work is handled by a queue and listener. Consider the diagram below: Therefore, when an async function (or an I/O) needs to be executed, the main thread relays it to another thread, allowing v8 (Javascript engine) to continue processing or running its code. In the event loop, there are different phases, like pending callbacks, closing callbacks, timers, idle or preparing, polling, and checking, with different FIFO (First-In-First-Out) queues.

14. Is there a way to decrease the load time of a web application?

Here are some ways to reduce load times for web applications:

Image Optimization: The file size of an image can be dramatically reduced by switching to a different file format. For example, GIFs work well for images with few colors, such as logos, JPEG is ideal for images with lots of colors and details, such as photographs, and PNG format is ideal for transparent images with high quality.
Keep JavaScript and CSS in external files: Embedding JavaScript and CSS in HTML documents forces them to be downloaded every time the HTML document is loaded. In this case, browser caching is not utilized, and the HTML document becomes larger. This is why you should always place CSS and JavaScript in external files; it is a best practice and simplifies maintenance.
Reducing redirects: Too many redirects will delay the loading time of a website. HTTP requests and responses are delayed each time a page redirects. Getting rid of unnecessary redirects on your site will reduce the load time of your site significantly.
Load CSS and JavaScript files asynchronously: Your website contains CSS and JavaScript files that can be loaded either synchronously or asynchronously. As part of synchronous loading, each file is loaded sequentially, in the order it appears on your site. As opposed to synchronous loading, asynchronous loading allows multiple files to be loaded simultaneously, boosting the performance of a website.
Minify HTML, CSS, and JavaScript: If you optimize the way your files load, your pages will load more quickly. You can do the same when it comes to HTML, CSS, and JavaScript code. By eliminating unnecessary spaces, characters, and comments, you can reduce the size of your files. This will make your web pages load faster.

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15. Explain dependency injection.

The Dependency Injection (DI) pattern is a design pattern for implementing the Inversion of Control (IoC). Dependent objects can be created outside of classes and made available to classes in different ways. Three types of classes are involved in Dependency Injection as follows:

Client Class: A client class (dependent class) is one that depends on the service class.
Service Class: Service (dependency) classes provide services to client classes.
Injector Class: This class injects the objects from the service class into the client class.

16. What do you mean by observer pattern?

If several objects are tied together in one-to-many relationships, the observer pattern is used. Every time one object is modified, then all of its dependent objects are automatically notified and updated. It falls under the behavioural pattern category. It describes the coupling between the objects and the observer and provides support for broadcast-type communication. The object that observes the state of another object is known as the observer, and the object that is being observed is known as the subject as shown below:

Full Stack Developer Interview Questions for Experienced

17. State difference between blue/green deployment and rolling deployment.

Today, the software is rapidly created and features are often changed based on customer needs, and then it is deployed into production. Each organization has its unique way of getting new applications into the production environment. Most organizations follow the standard deployment and release strategies such as Blue-Green and Rolling Deployment.

Blue-Green Deployment Strategy:

A deployment strategy like this creates two separate infrastructure environments i.e., blue and green. A blue environment contains older code (old version), while a green environment (production) contains the latest code (new version). There is only one live production environment at any given time.

Example: For instance, the green environment is live and is receiving all user traffic, while the clone (blue) is idle. Once a new version of an application is ready for release, it can be deployed to the blue environment for testing. As soon as the new release passes testing, application traffic is switched from green to blue. Blue then becomes the live production environment, and Green becomes idle, ready for testing the next release.

Rolling Deployment Strategy

Using this deployment strategy, old versions of an application are completely replaced with the new versions by completely replacing the infrastructure on which they run.

Example: When a new version must be deployed to all nodes, the new version is deployed to the first node while all other nodes handle end-user traffic. As soon as the new version is successfully installed on the first node, it will begin managing end-user traffic while the new version is being installed on the second node. The process is repeated until all nodes have been successfully upgraded to the new version.

18. Explain inversion of control.

IoC (Inversion of Control), as the name suggests, is a design principle in software engineering. With IoC, different kinds of controls can be inverted in an object-oriented design to attain loose coupling. The term “controls” refers to any other responsibilities a class may have other than its primary responsibility. These include controlling the flow of an application, controlling the creation of objects, or controlling the binding and creation of dependent objects. IoC allows classes to be loosely coupled, making testing and maintenance easier.

19. What do you mean by referential transparency in functional programming?

In functional programming, referential transparency is the key differentiating factor. An expression is considered referential transparent if it can be replaced or substituted with the corresponding value it computes or vice-versa without affecting the program’s result.Example: Imagine that we have an expression called four: val four= add(1,3)If four is used anywhere in our code, it can safely be replaced with add(1,3), 1 + 3 or 4 wherever it appears. Thus, all the expressions below are equivalent in meaning and output:

val eight = four + four
val eight_v2 = add(1,3) + add(1,3)
val eight_v3 = 4 + add(1,3)
val eight_v4 = 8

If we can swap back-and-forth between these expressions anytime, anywhere, without altering their meaning or output, then an expression is referentially transparent.

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20. State difference between normalization and denormalization.

Normalization and denormalization are the two main methods of altering the structure of a database.

Normalization	Denormalization
Normalization involves removing redundant data (multiple copies of data) from a database and storing consistent, non-redundant data.	It involves combining data from multiple tables into a single so that it can be queried quickly.
It primarily focuses on clearing out unused data and reducing duplicate data and inconsistencies from a database.	On the other hand, denormalization aims to achieve faster query execution by adding data redundancy.
During normalization, tables are reduced in number due to the reduction of data in the database.	Denormalization, on the other hand, involves integrating data into the same database and therefore the number of tables to store the data increases.
Data integrity is maintained by normalization. A change to the data in the table will not impact its relationship with the other table.	Data integrity is not maintained by denormalization.
It optimizes the use of disk space.	It does not optimize disk space.

21. In Java, what is a connection leak? How can you fix this?

If a connection is opened and forgotten about, this is known as a “leak” since each time it occurs, a connection is no longer available for reuse. Connection leaks occur when some database requests or transactions are not closed properly or are not committed, causing the connections to be abandoned and closed permanently. Java developers commonly experience Connection Leaks when using Connection Pools. In the case where there is a section of code that fails to close a connection properly, a connection will leak from the pool each time the section of code is executed. Eventually, if this situation continues, the pool will run out of connections, which is known as Pool Exhaustion. The application will hang once all available connections have been leaked. We can fix this by closing the connection and paying particular attention to any error handling code.

22. What is Promise and explain its states?

Callback functions are functions that can be passed to another function as arguments and executed there to complete a routine or action. Those functions depend on one another, so it could get quite messy with so many callback functions nested in so many layers. This is what is referred to as callback hell. As an alternative to callbacks in JavaScript, promises are used to handle asynchronous operations. In addition to handling multiple asynchronous operations, they provide better error handling than callbacks. Promises can be a better way for a user to read the code effectively and efficiently, especially when that particular code performs multiple asynchronous operations. The Promise object represents the result of an asynchronous operation (or its failure) and the resulting value. The promise is in one of the following states:

Pending: In its initial state, neither fulfilled nor rejected.
Fulfilled: Indicating that the operation was successful.
Rejected: Indicating that the operation failed.

23. State the difference between GET and POST.

GET and POST are two different HTTP request methods.

GET	POST
This method is used to request data from a certain resource (via some API URL).	This method is used to send or write data to be processed to a specific resource (via some API URL).
If you use the GET method to send data, the data is added to the URL, and a URL can be up to 2048 characters in length. Therefore, it has restrictions on data length.	It does not impose such limitations.
In comparison to POST, GET is less secure since data is sent as part of the URL. Passwords and other sensitive information should never be sent using GET.	It is a little safer to use POST than GET because the parameters are not saved in the browser history or the web server logs.
Everyone can see the data in the URL.	There is no data displayed in the URL.

24. Explain the Restful API and write its usage.

APIs (Application Programming Interfaces) are sets of rules and protocols that define how software programs or devices can communicate with each other. APIs that conform to the design principles of REST, or representational state transfer, are known as REST APIs. REST APIs may also be referred to as RESTful APIs. Using RESTful APIs, developers can create requests and receive responses via an HTTP request. REST API can also be used for mapping data from a cloud platform to a data warehouse or vice versa.

25. What do you mean by MEAN Stack?

MEAN stands for MongoDB, ExpressJS, AngularJS, and Node.js. It is a collection of JavaScript-based technologies for developing web applications. Despite being a stack of different technologies, all of them are based on the JavaScript language. It is an ideal solution for building dynamic websites and applications as it is a very user-friendly stack. With this free and open-source stack, you can quickly and easily build web-based prototypes.

Frequently Asked Questions

26. How to be a full stack developer?

To become a full stack developer, follow these six steps:

Plan your learning path according to your career goals
Learn the fundamentals, necessary technologies, and develop the skills you need to be a full-stack developer and necessary technologies.
Learn from tutorials and videos, but learn to code as well.
Based on what you learn, create your own project.
Make a portfolio of your work.
Start your job search and nail the interview.

27. How many types of full-stack developers are there?

Following are the most common types of full-stack developers based on their specific stacks:

MEAN Stack (MongoDB-ExpressJS-AngularJS-NodeJS).
MERN Stack (MongoDB-ExpressJS-ReactJS-NodeJS).
LAMP Stack (Linux, Apache, MySQL, PHP).
LEMP Stack (Linux, Nginx, MySQL, PHP).
Full-Stack Python.
Full-Stack Elixir.
Full-Stack Django.
Full-Stack Java.
Full-Stack Ruby on Rails.

28. Which full stack is best?

One of the most popular tech stacks is the MEAN stack (MongoDB-ExpressJS-AngularJS-NodeJS). MEAN stack has many applications, including cloud application development. MongoDB, Express.js, AngularJS, and Node.js are among the JavaScript technologies in MEAN used to build web applications.

29. Is full-stack development a good career?

Definitely, it’s a great career choice. Having a full-stack developer job is one of the most productive careers you can have, and its high level of responsibility makes it one of the most important careers in tech. Full-stack developers do not only specialize in front-end and back-end development but are also experts with a wide range of skill sets and knowledge. Full Stack Developers are in high demand and companies are willing to pay handsomely for those with the right skillset and diverse knowledge.

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30. How much do full stack developers earn?

A Full Stack Developer is one of the most highly paid professionals. In India, the average annual salary for a Full Stack Developer is around ₹6,66,697. With 1-4 years of experience, a full-stack developer earns an average of INR 6,53,006-10,00,000. Employees with between 5 and 9 years of experience can expect to earn between INR 12 and 17 lakhs per year.

Full Stack Developer MCQ Questions

Well-versed in programming languages such as Java, Python, Ruby, etc.

Familiar with front-end technologies such as HTML5, CSS3, JavaScript, etc.

Proficiency in development frameworks, including Spring Boot, Django, MyBatis, etc.

All of the above

Centralized online registration system

Cross-Origin Resource Sharing.

Centralized online resource sharing

None of the above

Reduce the number of redirects.

Image compression and optimization.

Minify HTML, CSS, and JavaScript.

All of the above

Blue-Green deployment strategy

Rolling deployment strategy

Recreate deployment strategy

Canary deployment strategy

Client

Injector

Concrete

Service

True

False

Callback Hell

Promise

Event Loop

None of the above

Linux, Apache, MySQL, PHP

Linux, Nginx, MySQL, PHP

MongoDB, ExpressJS, AngularJS, Node.js

MongoDB, ExpressJS, ReactJS, NodeJS

Has no bindings to ‘this’ or ‘super’, so it shouldn’t be used as a method.

Has no new.target keyword.

Not suitable for use as constructors.

All of the above

Normalization

Denormalization

Both A and B

None of the above

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Conclusion

A potential employer doesn’t expect applicants to know everything, whether they’re freshers or experienced. However, a well-prepared and enthusiastic candidate will undoubtedly stand out. In a full stack developer interview, candidates should be able to demonstrate excellent organizational skills and precision in their work. Also, honesty and transparency pay dividends over the long run.

In this article, we have covered the top 30+ Full-Stack developer interview questions & answers for freshers and experienced candidates so you can succeed in your next full-stack developer interview. Questions like those listed above are quick, insightful, and provide key suggestions that are vital to the interview process. If you review frequently asked full stack developer interview questions and answers, you increase your chances of getting hired. Make sure you review all the questions and answers.

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Top Full Stack Developer Interview Questions (2024)

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Top Full Stack Developer Interview Questions (2024)

Full Stack Developer Interview Questions for Freshers

1. To develop a project from scratch, what technologies and languages would you need or what skills a full stack developer should have?

2. Which language is the most preferred by full-stack developers?

3. Explain Pair Programming.

4. What do you mean by CORS (Cross-Origin Resource Sharing)?

5. What is Callback Hell?

6. Explain Long Polling.

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7. Can you tell me what are the latest trends in Full Stack Development? Also, how do you keep yourself updated about the new trends in the industry?

8. State difference between GraphQL and REST (Representational State Transfer).

9. What is CI (Continuous Integration)?

10. Explain the meaning of multithreading.

11. Explain the benefits and drawbacks of using “use strict”.

12. What are some of the uses of Docker?

13. Explain event loop in Node.js.

14. Is there a way to decrease the load time of a web application?

15. Explain dependency injection.

16. What do you mean by observer pattern?

Full Stack Developer Interview Questions for Experienced

Ever wondered how much you really know? It's time to put your brain to the test!

17. State difference between blue/green deployment and rolling deployment.

18. Explain inversion of control.

19. What do you mean by referential transparency in functional programming?

20. State difference between normalization and denormalization.

21. In Java, what is a connection leak? How can you fix this?

23. State the difference between GET and POST.

24. Explain the Restful API and write its usage.

25. What do you mean by MEAN Stack?

26. How to be a full stack developer?

27. How many types of full-stack developers are there?

28. Which full stack is best?

29. Is full-stack development a good career?

30. How much do full stack developers earn?

Full Stack Developer MCQ Questions

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Conclusion

Feeba Mahin

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