The Most Important Technical Interview Questions You Need to Prepare For

While some people might not find tech job interviews nerve-wracking, for most of us (even those with Computer Science or IT degrees), the interview process is the stuff anxiety dreams are made of.

While you’ll certainly have come across some of the standard interview questions you can expect in a tech job interview (think: behavioral questions, questions about your technical skill set, certifications, knowledge of project management systems and the development process) tech interviews are notoriously unpredictable. Hello, nonsensical curveball questions. 😏

It can leave you feeling lost when it comes to preparing.

But there’s no reason to panic. Ultimately, recruiters, tech companies, and other stakeholders are interested in your communication skills and your problem-solving skills (sometimes more so than your programming know-how).

And their questions are designed to reveal how you think and work through problems — not to trip you up or embarrass you.

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📌 Related: What Happens In A Technical Interview? Your Technical Interview Questions Answered

For this post, we compiled some of the top questions you can expect in technical interviews. To help demystify the experience, we spoke with hiring professionals who supplied key tech interview questions and some pointers for formulating answers — even to the questions nobody sees coming.

First, we’re covering the broad types of questions that CEOs and other managers tend to ask when interviewing candidates for technical positions. Then we cover more technical questions — the kind meant to test your actual coding know-how.

Table of Contents

  1. Common Questions Hiring Managers Ask in Technical Interviews to Find Out if You’re Right For the Job
  2. 8 Real Examples of Technical Interview Questions That Test Your Coding Skills

Common Questions Hiring Managers Ask in Technical Interviews to Find Out if You’re Right For the Job

1. “What do you know about our company?”

Sound obvious? Sometimes the best technical interview questions are — and they’re more revealing than you might expect.

Alan Hattman, Manager of Talent Acquisition at Peloton Technology, has a yikes-worthy story that proves that the importance of research can’t be stressed enough: While he was looking to hire a Director of Marketing, not one but two candidates thought they were interviewing for a different company with a similar name.

“They thought we were a bike company,” Hattman says. (Peloton Technology is a vehicle technology company. The interviewees had confused it with Peloton Cycle.) “They even talked about how they used our product and everything. So those were automatic fails. Do your homework. Research the job and the company you’re applying for.”

When it comes to reading up on a prospective employer, Jenna Kass, Recruiting Manager at Tableau Software, says she always appreciates when “candidates take the time to research our company from a business standpoint.” Before you walk into the interview, find out who the company’s competitors are and gather information about their audience or customers.

The last step is to build on your research with your own expertise. ShipMonk CEO Jan Bednar asks candidates for feedback about his company’s product—specifically for changes they’d make. His ideal response “would not only explain what they would like changed but also how they would change it.”

2. “What’s the most challenging/exciting project you have done in the past two years?”

Your work should lead the way in any technical interview and Lauren Thompson, Zillow’s Communications Coordinator, says that in addition to technical specifications, Zillow’s interviewers want to see “the innovation [an interviewee] comes out with from the project.” The goal of this technical interview question? To figure out what you’re passionate about, she says.

You should start preparing for this question long before you send out resumes, and a safe bet is to dig into each of your projects as you go to focus on what parts (of web development, app development, etc.) you’re passionate about, what motivates you, and what types of work you want to do in the future.

Then, practice articulating that list, so if an interviewer asks you to explain a project from your portfolio, you’ll have more to say than a simple list of specs.

Your answer might sound like: “I love 8-bit gaming, so I developed a C++ emulator for Chip-8. It combined my interest in digital preservation with getting to dust off my Tetris and Pac-Man skills. I’m looking forward to applying some of the C++ tricks I used to more projects in the future.”

3. “What kind of tech projects do you work on in your spare time?”

If you haven’t already picked up on it, passion goes a long way in tech — almost everyone I spoke to for this article mentioned it at some point.

Kevin Hayen, CTO of Let’s Be Chefs, considers self-directed creative work a critical piece of assessing entry-level applicants and veteran candidates alike. The way an interviewee answers these types of questions shows Hayen “what in tech they are really passionate about or if they even are passionate about tech” in the first place.

It doesn’t matter what your hobby is: Talk it up with all the genuine enthusiasm you have. Like many of these questions, it’s not the actual answer that interests Kevin — he says he doesn’t care if the answer is open source, DIY, or even just playing around.

Hayen says that this question also helps him figure out “how the candidate might fit into a particular team and what ‘bonus’ skills they might bring to the company” — things you didn’t even think to add to your resume but will make you a more well-rounded applicant.

4. “Tell me about the most difficult technical challenge you’ve encountered and how you resolved it.”

Bryan Petro, COO of GetMyBoat, asks this technical interview question to make sure prospective employees can do more than check off a box when a problem is fixed. “We’re not looking for people who can just churn through bugs,” Bryan says, “but people who can understand the big picture as part of a larger product team.”

So that you’re not up all night before an interview, wracking your brain for every challenge you’ve ever faced, try keeping a log of the times your skills were pushed to their limits and how you rose to the occasion as you work on projects. You don’t need to write essays here — a few bullet points to jog your memory will suffice.

5. “What technologies could you not live without?”

Stephen Negron of LegalTech Consulting, Inc. wants to know what tech skills candidates bring to the table, of course. But after that’s out of the way, he has a different line of questioning — a list of “revealing questions” that tell him about the interviewee’s life as a techie (and potential team member).

He asks:

  • Tell me about your computers at home. What’s your internet speed?
  • What are your favorite gadgets? Apps?
  • What kind of phone do you have?
  • What are your tech pet peeves?

“I really want to know if they practice what they preach, if they live the tech life, and if they have an understanding of the everyday tech frustrations,” he says.

This is a point that’s easy to overlook amidst loftier talk of expertise, but if you’re not consciously engaging with devices, apps, and websites, all the technical skills in the world won’t bridge that gap toward empathizing with the end user when it comes to designing your own products.

6. “What would you bring to our monthly bakeoff?”

“It may sound like a silly question,” says Max Schleicher, Digital Marketing Manager at Insureon, but this job interview question gives him insight into candidates that a resume simply can’t. It’s a twist on the curveball question — which usually shows an interviewee’s logic skills.

While he appreciates those questions, Schleicher wants to see creativity, social skills, and communication style. “Trust me,” he says. “You can learn a lot about someone from their baking preferences.”

There’s no wrong answer, whether it be a standard “brownies” or “double butterscotch blondies with almonds,” he says. The critical tell is whether interviewees “buy in, whether they’re excited, and how well they’re going to fit into the culture we’re working to create.”

This question has another purpose: Schleicher says that a question like this humanizes him and the company because he wants to win over the applicant, too. “We want to sell our culture and our sense of teamwork to new candidates. We want to attract candidates that buy into that,” he says.

7. “Tell me about a time you were asked to do something you had never done before. How did you react, and what did you learn?”

The key to working in tech isn’t knowing everything–that’s not even possible for multi-decade vets of the industry. For Brendan Browne, VP of Talent Acquisition at LinkedIn, this question boils down to the number one soft skill needed at LinkedIn: adaptability.

“Soft skills like adaptability are a hard thing to suss out but they’re critical for someone to be successful here,” Browne says. Projects change direction all the time, while departmental reorganizations and management shifts lead to priorities being rearranged. “Your ability to deal with these scenarios will impact where you’re best able to contribute at a company.”

As far as the best way to show your adaptability in an interview setting, Browne says he’s “looking for real answers, not the canned, stereotypical responses.”

Go with an experience from your career (a department re-org, a client changing their mind last minute) or personal life (becoming a parent, a cross-country move) that shows how you’ve been able to “adapt, persevere, and manage change.”

Not a particularly adaptable person? Don’t panic. Self-awareness is also a key trait Browne looks for. “You don’t need to pretend certain skills are your strong point if they aren’t. If adapting quickly is hard for you, that’s okay. You likely have other soft skills an employer wants (collaboration, culture fit, etc.), so play those up during your interview,” he says.

8. “How much does a first class one-way ticket from New York to Abu Dhabi cost on Etihad?”

ShipMonk CEO Jan Bednar doesn’t really expect anyone to know the answer—it’s the infamous curveball question. “Frankly,” he says, “we’d be a bit surprised if they did.” Then why ask it?

“Whether they guess $3,000 or $80,000 is functionally immaterial,” Bednar says. Instead, it’s all about the process. “What steps do they take to solve the question? Do they draw upon past experiences? Projections? General knowledge? These are the skills we want to see,” Bednar says.

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8 Real Examples of Technical Interview Questions That Test Your Coding Skills

In addition to the questions above, which assess your non-technical skills more than anything — such as your software development interests — hiring managers also ask technical, knowledge-based questions to determine your technical knowledge. In other words, they have to test you to make sure you have the right skill set for the job.

Whether you’re a Python pro, a Java developer, or a jack of all trades in terms of programming languages, there are language-specific questions or general programming knowledge base questions you’re expected to know, regardless of the job description.

For this post, we scoured the Internet for common questions hiring managers ask during technical knowledge-based interviews and how to answer them.

While being able to answer these questions will benefit all aspiring developers, front end developers in particular will want to know the answers to these questions.

📌 Related: Exactly What You Need To Know To Become A Front End Developer In 2021

Interview tip: when prepping for the various types of technical interviews you might face, we recommend Googling for technical interview questions and answers for your specific area of expertise (e.g. “front end developer interview questions”) to get a good idea of the range of questions that you may be asked and to practice answering them.

Even if you don’t know all of the answers right off the bat, with practice, you’ll be on your way to acing your technical interview in no time.

1. What is the main difference between Prototypal and Class inheritance?

From Temok:

“In JavaScript, inheritance is different from a lot of other development languages. In JavaScript, the object system is based on a prototype, not the class. Objects are only a collection of value pairs and names. As far as the inheritance is concerned, there is only one construct in JavaScript: objects. Each object has a private property that comprises a link to other objects, known as the prototype of that object.”

2. What does CORS mean and how does it work?

From Mozilla:

“Cross-Origin Resource Sharing (CORS) is an HTTP-header based mechanism that allows a server to indicate any origins (domain, scheme, or port) other than its own from which a browser should permit loading of resources. CORS also relies on a mechanism by which browsers make a “preflight” request to the server hosting the cross-origin resource, in order to check that the server will permit the actual request. In that preflight, the browser sends headers that indicate the HTTP method and headers that will be used in the actual request.”

3. What is ClickJacking?

From Fullstack Cafe:

“ClickJacking is an attack that fools users into thinking they are clicking on one thing when they are actually clicking on another. The attack is possible thanks to HTML frames (iframes).
Its other name, user interface (UI) redressing, better describes what is going on. Users think they are using a web page’s normal UI, but in fact there is a hidden UI in control; in other words, the UI has been redressed. When users click something they think is safe, the hidden UI performs a different action.”

4. What is the difference between let, const, and var?

From G2i:

“Originally, var was the only option JavaScript had for defining variables. In ES6, we got const and let as additional options. The important takeaways are:

  1. Variables defined with const cannot be reassigned.
  2. Const and let variables are block-scoped.
  3. Var variables are function scoped.
  4. Variables defined with var are hoisted.”

5. What is WCAG and what are the differences between A, AA, and AAA compliance?

From Digital Accessibility Center:

“WCAG stands for Web Content Accessibility Guidelines, which are part of a series of web accessibility guidelines published by the Web Accessibility Initiative of the World Wide Web Consortium.

  1. Single A is viewed as the minimum level of requirement which all websites, apps, and electronic content such as documents should adhere to.
  2. Double A is viewed as the acceptable level of accessibility for many online services, which should work with most assistive technology which is now widely available on both desktop and mobile devices, or which can be purchased as a third-party installation.
  3. Triple A compliance is viewed as the gold standard level of accessibility, which provides everything for a complete accessible offering, including all the bells and whistles which make the difference between a very good experience and an excellent one.”

6. How do you find the largest and smallest number in an unsorted integer array?

From Faceprep:

Method 1: Traverse the array iteratively and keep track of the smallest and largest element until the end of the array.
Method 2: Traverse the array recursively and keep track of the smallest and largest element until the end of the array.
Method 3: Sort the array using STL and return the first element as the smallest element and the last element as the largest element.

For example, consider the array.
arr = {1, 2, 3, 4, 5}
Smallest element : 1
Largest element : 5″

7. What is a closure?

From Eric Elliot at JavaScript Scene:

“A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function. In JavaScript, closures are created every time a function is created, at function creation time.

To use a closure, define a function inside another function and expose it. To expose a function, return it or pass it to another function.

The inner function will have access to the variables in the outer function scope, even after the outer function has returned.”

8. What are the differences between null and undefined?

From That JS Dude:

“JavaScript has two distinct values for nothing, null and undefined.

undefined

undefined means that the value of the variable is not defined. JavaScript has a global variable undefined whose value is “undefined” and typeof undefined is also “undefined.”

Remember, undefined is not a constant or a keyword. undefined is a type with exactly one value: undefined.

Assigning a new value to it does not change the value of the type undefined.

8 Ways to get Undefined:

  • A declared variable without assigning any value to it.
  • Implicit returns of functions due to missing return statements.
  • Return statements that do not explicitly return anything.
  • Lookups of non-existent properties in an object.
  • Function parameters that have not passed.
  • Anything that has been set to the value of undefined.
  • Any expression in the form of void(expression)
  • The value of the global variable undefined

null

null means empty or non-existent value which is used by programmers to indicate “no value.”

null is a primitive value and you can assign null to any variable. null is not an object, it is a primitive value.

For example, you cannot add properties to it. Sometimes people wrongly assume that it is an object, because typeof null returns “object.”

Btw, null == undefined ref: history of typeof null.”

Having a set of tech skills is one thing, but communicating your ability to use them practically, creatively, and efficiently is what will help you land the job.

As I interviewed hiring professionals for this article, multiple people told me that surprise brain teaser questions are all about your thought process, not your answer — so don’t be afraid to give follow-up explanations as you go along.

So if you find yourself face-to-face with one of these tough technical interview questions, take a breath, don’t get flummoxed, and talk the interviewer through your thinking. That’s all they want to hear.

*This post has been updated from an original version written by Scott Morris*

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