FULL Stack Interview Questions and Answers – Top 50 Updated

1. What is your favorite language and why?
Answer: Full Stack Web Developers work with a multitude of languages. Having just one loved coding language might be an alarm signal. Ideally, a candidate must have a few languages that he loves, preferably, some with which he can design the front end and others with which he can take care of the back end. A candidate should be able to demonstrate that well and remember to include the basic most used ones like HTML, CSS, Python, etc.

2. Are you aware of design patterns?
Answer: While answering this question you should show your ability to understand common errors that might creep in while creating web applications. If your knowledge is formal and deep, you must push the employer to gain confidence in the experience you possess in understanding a clean and readable code.

3. What is an application server?
Answer: An application server allows both the creation of web applications and also a server environment to launch the application.

4. What role do you prefer, technical or managerial?
Answer: Full-stack developers are capable of handling both technical and managerial roles depending upon their desire. In the technical field, they get to work on various projects along with other team members. While in the managerial field they can lead projects with suggestions or ideas for betterment.

5. Why did you decide to pursue a career as a full-stack developer?
Answer: In every context, building rapport is important. In the context of interviewing a candidate for a technical position, many people forget to ask essential rapport-building questions.
Asking an interviewee why those chose a career as a full stack developer can help you build a professional relationship and gain insight into their career goals, passions, and experiences.
As an interviewer, you can more easily build upon your interview script with some personal information. You would be surprised how far a warm conversation can go. It can make interviews far more productive and enjoyable for both parties.

6. Provide an example of a web application that you’ve built, and which technologies were used to build it. What considerations did you make when deciding on the tech stack to use?
Answer: This question is asked to get a sense of how a developer thinks. It also speaks to what considerations they make when settling on a toolset. The interviewee should respond as specifically as possible, even if the decision was made because of pre-determined architectural standards or company-mandated technology preference.

7. What design principles or patterns have you incorporated into previous projects?
Answer: This question is used to test a candidate’s design capabilities and their ability to implement these skills into their work product. Interviewees should have a general awareness of design principles like DRY, KISS, YAGNI, SOLID and patterns such as Factory Method and Singleton. Good IT professionals should be able to explain a project where one or more of those principles were implemented.

8. What Is Object-Oriented Programming?
Answer: Object-oriented programming (OOP) is a programming paradigm based on the concept of “objects,” which may contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods. A feature of objects is that an object’s procedures can access and often modify the data fields of the object with which they are associated (objects have a notion of “this” or “self”). In OOP, computer programs are designed by making them out of objects that interact with one another. There is a significant diversity of OOP languages, but the most popular ones are class-based, meaning that objects are instances of classes, which typically also determine their type.

9. What is Continuous Integration?
Answer: 
Continuous Integration is using codes that are built and automated for testing or production. This allows developers to deploy codes easily during the time of production. Developers need to integrate a code every day during the building stage. Every code is checked automatically. After that, codes are deployed to production without human intervention. This can detect problems quickly and in many early stages.

10. Describe a time when you made a mistake in your duties. How did you rectify it?
Answer: Candidates should acknowledge the significance of diligence and how programming oversight can derail an entire company’s business operations. Look for stories where candidates erred, rectified their error and learned a valuable lesson from it. 

11. What coding projects are you currently working on?
Answer: Good programmers are always coding, whether it be at work or for recreational reasons. Look for candidates who find creative uses for code outside of their work, as this is indicative of a highly skilled programmer.

12. When working on UI features, or web front ends, describe your approach to collaborating with designers?
Answer:
This will help you understand a candidate’s ability to collaborate and incorporate the work of others into their product. In addition, it gauges their attention to user experience. The candidate should respond with a situational example of a time they worked closely with designers, and what the unique outcome was as a result. Pay close attention to when they use “I” vs. when they use “we” as they explain their collaborative efforts.

13. How do you stay aware of new technologies related to full-stack web development?
Answer: This question is asked to find out how involved or uninvolved a candidate is in the technology community, Wallenberg said. Interviewees should respond by describing a few meetups they are part of related to JavaScript, or personal projects that they have displayed in GitHub, for example.

14. What is multithreading and how is it used?
Answer: This is a full-stack developer interview question that tests your computer architectural knowledge. Multi-threading is a process of improving the performance of CPU. This is done by executing multiple processes or threads that can be supported by the operating system.

15. How do you get to know about the latest trends being a full stack developer?
Answer:
As a full-stack developer, one should stay updated with all the latest trends. We must test new software every now and then. We must acquire new skills and this will exhibit full-stack developers as passionate, knowledgeable individuals. Reading books, blogs, attending seminars can keep us updated.

16. What, in your opinion, is the most important quality in a Full Stack Developer?
Answer: Candidates should list good organization skills and attention to detail as the most important qualities in a Full Stack Developer.

17. In your career, has there been a time when you made a big mistake in programming? How did you compensate for it later?
Answer: Sometimes flaws are common during a project. But it is the duty of a full stack developer to ensure that such things do not happen at all. If there was a mistake, then it would have been a big loss to the company. This will require advanced technical skills to rectify. Eventually, the developer learns how to rectify and compensates. Such incidents remain as good learning experiences in our careers.

18. How do you develop a successful Continuous Integration process?
Answer: Firstly, we must maintain an idea for the code of the project. Then we must automate the build which should be self-testing. Codes should be integrated by everyone on the build every day. The build must be quick and updated according to the requirements of the production. Finally, the deployment process should be automated. With these steps, Continuous Integration can be successful in detection problems and making production quick.

19. Do you have a portfolio I can see?
Answer: Reading a resume, going through technical questions, and vetting the candidate with cultural questions can be tremendously helpful. None of these activities are as enlightening as peering at a portfolio.
A portfolio of live websites, web apps, and completed projects will be able to tell you just how skilled, talented, and devoted a full stack developer is to their craft.
Be sure to ask for a development portfolio as soon as possible so you can get a better feel for the candidate’s work.

20. What is your experience working with RESTful APIs and web services?
Answer: This question will test a candidate’s ability to develop applications that communicate through the web with over applications. Interviewees should respond with examples of APIs they have developed personally, or times where a service they built has used an already existing API.

21. How familiar are you with web programming languages HTML, CSS, PHP, and JavaScript?
Answer: Full-stack web developers know every aspect of web programming, web development, and app engineering. They know how to code the front-end of a website (with HTML, CSS, and JavaScript) and manage the back-end (with PHP or Python and MySQL).
A great full stack developer will be able to create and edit source code as well as understand how to utilize web development frameworks, understanding how to utilize existing codebases.

22. What does “favor object composition over class inheritance” mean?
Answer: This is a quote from “Design Patterns: Elements of Reusable Object-Oriented Software”. It means that code reuse should be achieved by assembling smaller units of functionality into new objects instead of inheriting from classes and creating object taxonomies.

23. How many years of experience do you have as a full stack developer?
Answer: 
Asking an interview about how many years of relevant experience they have is an absolutely essential question.
Obviously, the amount of experience your projects require is reliant on many details, such as:
How large your development team is
Whether or not you have senior full stack developers on your team
How experienced your software project manager is
How complex your app development projects are
Whether or not you’re looking for freelance full stack developers for hire or full-time full stack developers
For reference, a junior full stack developer may have 1-3 years of experience. A more experienced full stack developer may have upwards of 5-7 years. 

24. How did you debug a difficult program in any of your previous jobs?
Answer: Debugging is an extraordinary talent in full-stack developers. As an individual, we can debug a difficult program with software skills. However, before debugging analysing the problem is very important. Understanding why it actually led to such a problem should be rectified from the next project. Also, joining with the team to debug issues can be a great way to overcome such issues. 

25. What technologies, programming languages, and frameworks would you use if you had to develop a project from scratch in only one month?
Answer: The objective of this question is to challenge the candidate to answer a complex question in a short amount of time, said Cristian Rennella, vice president of HR and co-founder of elMejorTrato.com. “This way you can distinguish the best full-stack developers because those who can answer this question in a clear and simple way will be the most appropriate,” Rennella said. “Those who have a difficult time to transmit their thoughts will be the least.”

26. How would you store a user’s password for an online portal?
Answer: This question seems simple, yet quickly reveals a full stack developer’s security knowledge, said Paul Leduc, director of technology at RingPartner. “There are lots of ways to store passwords, but only a few could be considered secure from front-end to back-end,” Leduc said. “Ideally, a developer would be able to articulate which specific security features are essential and explain how the user’s data would be protected from the UI through to the back-end and databases. This is also a great opportunity for a developer to highlight how she or he has handled a similar scenario in the past, which provides insight on character and helps the interviewer see how the candidate could be a culture fit.”

27. What are your design patterns?
Answer: Full-stack developers generally will be aware of basic design patterns like UI design, GUI design, UX design, prototype design and database working principles. They are compulsory for a full stack developer to excel in this field.

28. Provide an example of a web application that you’ve built and what technologies were used to build it. What considerations did you make when deciding on the tech stack to use?
Answer: “This question is asked to get a sense of how a developer thinks and also speaks to what considerations they make when settling on a toolset,” said Paul Wallenberg, unit manager of technology recruiting services at LaSalle Network. “Interviewee should respond as specifically as possible, even if the decision was made because of pre-determined architectural standards or company-mandated technology preference.”

A related question might be whether or not a candidate considers themselves heavier on the front-end or back-end, said Christy Cifreo, senior recruiter at Synergis. “Give an example of a recent project to include how and why you developed either on the front-end or back-end,” Cifreo said. “We would want to get some basics of where they are most experienced. Depending on the specific job, we might be looking for someone that has more experience in one area over the other.”

29. What are you coding currently?
Answer: A person who loves technology is always working with it. Whether it be for your company or for your own recreational reasons. Good programmers will always have something to share. Candidates who code willingly for personal learnings will always stand out here.

30. What is the best implementation or debugging you have done in the past?
Answer: This is a tricky question. This will actually give the hiring manager an idea of both the complexity and the style of projects you have done in the past. You should explicitly mention the issues you faced and the measures you took to overcome that roadblock. You can additionally speak about the learnings you earned from the issue.

31. Do you enjoy management or execution more?
Answer: Every senior professional will be asked this full-stack web developer interview question. Recruiters want to know if you want to stay in a technical role or would want to switch to a managerial position. They also at times might push a bit and ask if you prefer to work alone or in paired groups. It’s important, to be honest here. The company’s requirements might be different from your interests, so it is ideal that the expectations are set straight from the get-go.

32. What is Pair-Programming? Have you ever done it?
Answer: Pair Programming is one of the core elements of extreme programming which involves two developers to work on the same terminal. While one developer is called the “Driver” who types the codes, the other developer called the “navigator” is responsible for reviewing the codes.

33. How do you keep yourself updated about the new trends in the industry?
Answer: This is a typical question to understand your involvement in technology. A good way to demonstrate your involvement in continuous learning would be by speaking about the community meetups you visit. You can also talk about the webinars and the forums you regularly attend. If you have personal projects on which you apply your skills, this is a good time to showcase that as well.

34. What’s the most recent thing that you have learned?
Answer: This question is used to probe the authenticity of the information you furnished in your last question. It is important that you are aware of the latest in the industry and have a pulse of what’s happening. You might talk about a website that you tested recently, or talk about an obnoxious case study about a serious bug you recently read about. A point to note, never give the interviewer the impression that you have learned nothing in the past 6 months. This is a fast-changing tech game, and being up-to-date with the current trends is an absolute must.

35. What are the most important qualities that a Full Stack Developer must have?
Answer: A full stack web developer interview will surely be incomplete without this question, especially at a freshers level. A candidate should take time to talk about the competency required in various coding languages being the foundation stone on which a good professional can be built. He should talk about coordination skills that he would need while working in a team and mark excellent observation skills as a prime factor in working well in this role.

36. Which technologies and languages would you need to develop a project from scratch?
Answer: This is a hypothetical question geared at understanding the level at which the hiring manager will gauge your readiness to start the job. It is an easy way to distinguish a good full stack developer from someone who is an amateur. People who have difficulty transmitting their thoughts will have bleak chances of getting through at this point.

37. Give an example of a project you have worked on and the technologies involved. How did you make these choices?
Answer: This helps in knowing the methodology of the full stack web developer and also gives an idea of his sharpness and precision in choosing the right toolset. You need to be as specific as possible and go in-depth while speaking about the reason for choosing a particular toolset. Show a balance between your ability to develop both on the front-end and the back-end of the web application. It is okay to show that you have more experience in one side of the development game than the other but to demonstrate that you have the ability to work on both the ends of the application.

38. What is the biggest mistake you did in any of your projects? How did you rectify it?
Answer: As they say, ‘No man is an island’. Similarly, you can’t be working on technology and be right all the time. That is not imaginable. You need to be honest here and talk about a mistake that you think was serious. To add to it, speak about your learnings from this mistake and explain the procedure you adopted to minimize the damage done.

39. Why is closing the Cursor required during explicit cursor development?
Answer: It is important because it will consume system memory while it is inactive state and if it is not closed or terminated then it won’t let the other things in the memory as memory will be occupied and later on it will be full. Hence, deletion is necessary.

40. E-List some common ways to reduce the load time of a web application?
Answer: There are quite a lot of ways to reduce the loading time of a web application like enabling browser caching, optimizing images, minifying resources, minimizing HTTP requests and reducing redirects.

41. What’s your favorite language, and why?
Answer: This is a good question to warm a candidate up before diving into more technical ones, said Jason Ayachi, co-founder of RampUp.
“For a full stack developer, we’re looking for them to answer with a variety of languages rather than just having one favorite language,” Ayachi said. “We also love to hear that they’re playing around with a few new languages. This shows us that they’re really engaged with the industry and have a curious-passionate mind.”

42. What is Long Polling?
Answer: Long Polling is a web development pattern that is used to surpass pushing data from the server to the client. By using a Long Polling pattern, the Client requests information from the server. If the server does not have any information about the client, the server holds the request and waits for some information to be available rather than sending an empty resource.

43. What kind of role do you enjoy most?
Answer: For more senior developers, it’s important to let a potential employer know how much you want to stay in a purely technical role, and how much you want to move toward management, according to Gary Verhaegen, a full stack developer at Sparrho. This helps make sure you are a good fit for the company.
A related question would be, “Do you enjoy working in a paired programming environment, or do you prefer to work alone?” This question can help determine how much team collaboration a candidate has experience with, Cifreo said.

44. What is your current project that you are working on?
Answer: This displays the coding knowledge of a full stack developer. One has to constantly work with projects and write codes to master the job. Web designing is a great way to improve the skills of full-stack developers. Web development is what most companies expect in full-stack developers too. Telling about the recent personal projects and their scopes can help to answer this question.

45. According to you which is the most important quality of a full stack developer?
Answer: 
Full-stack developers should be good in organization skills, language, and technical skills, being open to suggestions, developing new programming strategies and staying updated.

46. Which is your personal favourite language?
Answer: Rather than explaining about one favourite, full-stack developers are expected to tell about most of the languages they are aware of. Since full-stack developers are well-versed with both front end and back end, telling about both languages is good. Also about some basic web languages like HTML, CSS and JavaScript. They can also tell why they like popular languages namely Python, MEAN, LAMP, Ruby on Rails.

47. What is CORS?
Answer: CORS also known as Cross-Origin Resource Sharing is a process for accessing various web resources on different domains. With the help of CORS, web scripts can be integrated more openly with external content of the original domain. This further leads to better integration between web services.

48. Can you relate of an experience when you found your colleagues code to be inefficient? How did you deal with it?
Answer: This helps to determine a candidate’s quality standards and also gives an impression of his team playing skills. You must demonstrate that you have high-quality assurance standards, and show comfort in pointing out flaws or for that matter bugs to others. However, you must pay focus on portraying that you are good at giving positive feedback, getting the work done without creating resentment.

49. What’s the most puzzling programming challenge you have come across recently?
Answer: Speak about the most recent bug or a discrepancy you came across and explain how you went ahead to overcome it. Tell the interviewer that you are a person who believes in collaborative work. Depict how you could solve the issue with the help of a colleague, online community or mentor. It is always good to ask when you don’t know.

50. Explain about a website that you created and how you did it?
Answer: Full-stack developers use a lot of tools for developing a project or website. The applicability of these tools should be comprehended well by the developers. Website development is the best way to understand them. Explaining web designing tools for the front end and back end development is necessary.

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