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30 Full-Stack Developer Interview Questions

The rapid advancement of technology has encouraged businesses to deploy the latest technologies for product development. This has sparked the demand for full-stack developers due to their knowledge of various programming languages. 

The future is yours if you’re an aspiring candidate. However, knowing common full-stack developer interview questions helps avoid uncertainty and boost confidence during your first interview. 

We’ve curated a list of popular questions below to help you breeze through your interview.

Top 30 Interview Questions for Full-Stack Developers

Interviews can be daunting, but with the right focus, approach and preparation, you can feel confident walking into the interview. Prepare some of the most popular Full-Stack developer interview questions below and you’ll instantly feel better about the interview.

1. Tell Us About Your Favourite Programming Language 

As a full-stack developer, you’re bound to work with several programming languages. So, mentioning a single language might not be a good idea. Instead, consider naming some front-end and back-end languages. 

“I like different programming languages to handle front-end and back-end development. My top favourites include CSS, HTML, Python, and Javascript as they make my work more seamless.”

2. If You Had a Few Weeks to Develop a Project, Which Programming Languages and Technologies Will You Use?

Answering a complicated question right away is certainly challenging. However, you can demonstrate your expertise by giving a concise, clear answer. 

Make sure your answer sheds light on your industrial knowledge. 

“To begin with, I’ll observe the nature of my job. If I were to write software for a web page, I’d prefer using JavaScript for the front end and Java or Python for the back end. However, I would shift my choice to C or C ++ for an embedded system and C# for a video game.”

3. Why Did You Choose Full Spectrum While Having the Choice Between Front-End and Back-End Development?

Sticking to one area would also help you land a job as a developer; why did you then opt for a full-stack developer role? 

The hiring manager wants to see whether you know the importance of the position and its contribution to a business. 

“I think choosing between front-end or back-end development would have deprived me of seeing the bigger picture when assessing a program or a website. I don't particularly appreciate sticking to one side of the coin but rather exploring various facets of a subject. I also stress the importance of being a T-shaped person. Having deep knowledge in a single area and a broader base of general knowledge gives me a sense of fulfilment.”

4. Describe Your Typical Day as a Full-Stack Developer In Your Previous Job

Because full-stack developers have a lot on their plate, the recruiter wants to know how you handled everything efficiently at your previous job. 

“In all honesty, I had to juggle various tasks during my previous role. It was common to jump from coding to fixing a networking problem and meeting clients in a single day. However, my organisational and time management skills helped me multitask without compromising work quality.”

5. Tell Us About a Time You Struggled With An Implementation Problem

Although we strive for nothing short of excellence, no man is an island. You’re bound to encounter issues as a full-stack developer. In fact, if you haven't, you lack experience. 

So, the recruiter doesn’t care about the details of your answer; they want to know whether you’re willing to talk about your flaws and what you’ve learned from them. 

“Although I’ve encountered numerous issues during my past work, a complicated one was where the site broke after an upgrade. Luckily, I’ve always actively communicated with my peers. So, they were quick to jump in and take over. This made me realise the importance of teamwork.”

The hiring manager wants to know whether you’re an enthusiastic learner. Because passionate employees significantly add to a company’s growth, the recruiter prefers candidates with a keen interest in the field. 

Someone eager about the field would naturally keep themselves updated with the industry trends.

“I love to attend community meetups, webinars, and forums to keep myself abreast of the changing trends and emerging technologies.” 

7. Tell Us About Something You Learned a Few Days Back

The interviewer is playing smart, connecting the dots between the two questions and probing about your authenticity. Because you demonstrated you keep yourself updated, they want to know if you learned anything new recently. Refrain from giving the impression that you learned nothing in the past few months. 

“I read about an intriguing case study regarding a bug. It helped me learn the quickest ways to find the bug source and eliminate it timely. This helped me boost my work efficiency.”

8. What Are the Most Significant Qualities of a Full-Stack Developer? 

The interviewer knows what qualities they seek in their next ideal candidate. They’ll ask this question to see if your answer aligns with their idea of “significant qualities.” Essentially, you’ll talk about YOUR qualities, and the recruiter knows it. 

So, if you manage to hit the bull’s eye, you’re in. 

“I believe coordination and observation skills are of utmost importance. A full-stack developer who knows how to work with a team and has excellent attention-to-detail skills reduces the chance of project errors and boosts project efficiency.”

9. How Would You React After Finding Code Inefficiencies In Someone Else’s Work?

Will you ignore someone’s code inefficiencies because of your low-quality assurance standards or provide constructive feedback for the best outcome? 

Your potential employer wants to know your approach when working as a team member. 

“I tend to get uncomfortable upon finding someone’s code inefficiencies. However, I cannot help but point it out to meet quality work standards. Nonetheless, I use polite phrases like “It would help if you….” “Can you please re-check…” “I wonder if we can revise…” to get the work done without resentment.”

10. What Do You Enjoy More, Management Or Execution? 

Hiring managers want to know if you want to stay in a technical position or scale up to a managerial role. 

Make sure you’re upfront about your choice and avoid answering to please them. Here are example answers for either role. 

“I prefer using computer systems and clever tactics to tackle the client-side and server-side of the application. Directing people is challenging for me.”

“I believe I perform well in the management position, given my leadership and interpersonal skills. The opportunity to learn, adapt, and help people succeed makes me happy.”

11. How Would You Reduce a Web Application’s Loading Time? 

Optimising a website adds to work quality. The hiring manager wants to test your skills and how you leverage them for the best performance. 

“There are several methods to minimise an app’s loading time. However, I generally optimise images and caches, minify resources, reduce redirects, minimise HTTP requests, and remove unused files to improve loading time.”

12. What Is Pair Programming?

Because pair programming improves code quality, reduces errors and bugs, and allows for faster training, the recruiter wants to know whether you’re familiar with it or have done it in the past. 

“Pair programming involves two developers working on the same terminal. One types the code, and the other reviews it. The former is called the Driver, while the latter is termed a Navigator.”

13. What Do You Know About Design Patterns?

The interviewer wants to know if you’re familiar with solutions to common problems that arise during software design. Of course, your knowledge will help resolve project errors. 

“Three primary design patterns are structural, creational, and behavioural. Structural design pattern organises different objects and classes to provide functionality. The creational pattern involves object creation. It further divides into object and class creational patterns. Finally, the behavioural design pattern identifies communication patterns between objects.”

14. What Is Multi-threading?

Because multi-threading significantly contributes to a program by allowing different parts to run simultaneously, the recruiter is willingly testing your knowledge. 

They want to know if you can minimise system resource usage, improve scalability, and boost inter-process communication when working with different programs. 

“Multithreading provides multiple threads for concurrent execution and maximum CPU usage. It enables several threads to exist such that they execute separately while sharing their process resources within the process context.”

15. Do You Think a Full-Stack Developer Needs Soft Skills? 

Employees today seek soft skills as much as hard skills. Therefore, they might want to know if you possess specific personality traits that can up their business game. 

“I believe soft skills are as important as hard skills. For instance, if a full-stack developer is well-versed in programming languages and knows their way around the latest technologies, their knowledge won't mean much if they fail to communicate it with their peers - hence the need for communication skills. Likewise, efficient problem-solving and attention-to-detail skills are also crucial.”

16. What Technical Skills Should a Full-Stack Developer Possess?

This is a tricky one. The recruiter wants to know YOUR technical skills, not those of some random full-stack developer. Carefully think through the answer and respond. 

“I think full-stack developers are the jack of all trades. Therefore, the list of technical skills is rather long. They must have a hang of programming languages like Python, Java, Ruby, PHP, C++, etc. Besides, knowledge regarding front-end frameworks like bootstrap, JavaScript, ReactJS, and back-end frameworks like NodeJS, Express, Django, etc., is vital. They must also understand popular databases and have excellent designing ability to become a successful full-stack developer.”

17. What Is Polling?

You’ll be tested with several field-related questions. So, if the interviewer asks you a few in a row, it’s no surprise. Get hold of yourself and answer patiently. They would be general questions for the most part. 

“Polling refers to when a client repeatedly asks the server for new data. It can be long polling or short. The former passes the data from the server to the client without delay. The latter, on the other hand, is AJAX-based and involves fixed delays.”

18. Can You Tell a Few Differences Between GET and POST?

Another relatively simple field-related question to judge your knowledge. Here’s an example answer.

“GET requests data from a particular source, whereas POST sends data to a server to create a resource. You can bookmark GET but not POST. Likewise, GET parameters can appear in browsing history while POST parameters aren’t saved. Lastly, GET displays data in the URL while POST doesn’t.”

19. How Will You Keep Bots from Scraping a Publicly Available API?

Because bots can reduce the loading speeds and hinder the API functionality, a full-stack developer is expected to know how to fix the problem. 

“I would first implement throttling to keep a specific device from making a certain number of requests within a given time. In the event the device exceeds the number, they’ll see Too Many Attempts HTTP errors. I might also stop requests based on user string or generate season access tokens for the users.”

20. What’s the Difference Between Normalisation and Denormalisation? 

There isn’t a secret sauce to answering this question. You only need to define both terms to demonstrate your knowledge. 

“Normalisation helps reduce data inconsistency and repetition from the table. It maintains data integrity and optimises disk space usage. On the flip side, Denormalisation adds redundancy to implement queries. It doesn't maintain data integrity nor optimise disk spaces.

21. How Would You Optimise a Website to Make It More Efficient?

Every company appreciates an efficient and scalable website; the one interviewing is no different. Your potential employer wants to know if you’re familiar with the tricks of optimising a website. 

“There are endless ways to optimise a website. However, my favourite site optimisation methods are minimising DNS lookups, leveraging caching, reducing request size, specifying graphic dimensions, and executing gzipping.

22. How Would You Describe Continuous Integration?

What’s better than knowing code errors before integration? That’s precisely what the hiring manager wants to test. Do you know how to enhance workflow through simple everyday practices? If yes, you’d likely know the answer to this question. 

“Continuous integration involves full-stack developers integrating code into a shared repository. This is done regularly to identify issues initially. The automated tools in the CI process highlight the code accuracy before implementation.”

23. Explain a Few Pros and Cons of Using “Use Strict”

You might not be familiar with Use Strict as a budding full-stack developer. However, the interviewer might ask you to discover if you’ve dug deeper into the field or are only focusing on surface-level knowledge. 

“Use strict offers several benefits. For instance, it detects common coding mistakes by throwing errors, disables confusing features, and gives an error in the event of unsafe actions. However, there’s no rose without a thorn. The feature also has a few downsides. For instance, developers may encounter issues when concatenating scripts in various strict modes. Besides, two primary features, function.arguments and function.caller, are no longer accessible.”

24. What Is Event Loop In Node.JS?

If you’re familiar with the event loop, perhaps you have a sound understanding of Node.JS, which is a plus. Concisely describe what an event loop is. 

“Event loop allows for asynchronous programming. Because every function in JS occurs on a single thread, you can form an illusion of multi-threading. So, during the async function's execution, the primary thread transfers it to another, enabling further processing.”

25. What Is CORS?

Budding and professional full-stack developers are familiar with CORS. Your hiring manager expects you to summarise a meaningful explanation within a few lines.

 

“CORS refers to cross-origin resource sharing. It uses HTTP headers to access different web resources on various domains. It allows developers to integrate web scripts effortlessly with external content of the actual domain. As a result, CORS enables seamless integration between web services.”

26. What Is Referential Transparency? 

Simply define what you’ve been asked. Get straight to the point and avoid mentioning anything unnecessary. 

“It is often used in functional programming to change an expression without altering the program’s result. So, regardless of whether the input is used as the original value or reference, it doesn’t change the program’s behaviour.”

27. Tell Us About the Biggest Mistake You Made In Any of Your Past Projects

You cannot work with the technology and expect not to encounter issues. It’s impossible. Your potential employer wants to see if you acknowledge your mistakes and are honest regarding your work. 

Talk about any mistake you committed during your work and explain how you fixed it. Tell them how collaboration has contributed to your learning. In other words, follow “One of the biggest mistakes I made….” with “It made me realise the role collaboration plays in minimising project errors and optimising processes.”

28. Can You Name a Few of the Latest Full-Stack Developer Tools?

Early on, you claimed that you stay up-to-date with the latest industry trends; your hiring manager wants to know if you were being honest. Take a deep breath and name a few efficient full-stack developer tools. 

29. What Qualities Make You a Better Candidate?

How do you stand out from the crowd? What qualities give you an edge over other applicants? What personality traits make you valuable enough to be considered by the company?

We recommend talking about your non-technical skills. However, avoid boasting and maintain a polite tone. 

“I think my problem-solving skills set me apart from other candidates. I have been good at problem-solving since childhood. However, working as a full-stack developer and handling various problems has honed my skill. Every new day brings a new challenge, which keeps nurturing my analytical skills.”

30. Where Do You See Yourself In the Next 5 Years?

Candidates with no goals are a huge turn-off for employers. Of course, nobody knows what the future holds; planning is a must. 

Employees who plan about their goals are seen as passionate and enthusiastic members that can level up any company. 

We recommend keeping the answer company-relevant to pique the interest of your potential employer. For instance, try something like: 

“I would like to see myself in an XYZ position in your company.” 


Let them know you’re willing to work with them long-term and contribute to their growth.

FAQs

The best way to prepare for a full-stack developer interview is to research the company and review its stacks. Besides, preparing field-related interview questions can help minimise tension and uncertainty, improving your performance during the interview. 

How Do I Introduce Myself as a Full-Stack Developer?

The best way to introduce yourself as a full-stack developer is to talk about your past experience and projects. Discuss the courses you’ve taken and the projects you’ve completed successfully. Continue the conversation by mentioning why this job interests you.

Conclusion

No employer expects you to know everything, whether you’re an amateur or an experienced candidate.

Preparing for common full-stack developer interview questions will ensure you don’t. Besides, taking a full-stack software development course at UCD Professional Academy can help boost your confidence during the interview. 

The more technical and non-technical insights you have regarding the subject, the better. Fortunately, the course provides a good grasp of the subject to newbie and pro-full-stack developers alike.