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Technical interviews: A guide for interviewers & candidates

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Introduction

Let’s face it: Technical interviews can be burdensome and unpleasant—for interviewers and candidates alike. For hiring teams, designing interview and assessment questions that accurately assess a candidate’s technical aptitude, problem-solving skills, and ability to collaborate can be a challenge. Candidates, meanwhile, face the pressure of demonstrating their technical knowledge and skills while communicating effectively in what is often a stressful interview context. 

Here at CodeSignal, the leading technical interview and assessment platform, we have spent countless hours developing solutions to make technical interviews less painful for both interviewers and candidates. Hiring teams who use CodeSignal benefit from a cohesive platform that supports pre-hire screening assessments and live technical interviews built around the same advanced integrated development environment (IDE), which creates a seamless experience for candidates as they progress through your hiring funnel. 

Working with hundreds of top companies, we’ve learned what makes a great technical interview—and what interviewers and candidates need to know about the tech hiring process. We’ve distilled this knowledge into this comprehensive resource designed to help both interviewers and candidates navigate the technical interview process. This guide equips interviewers with effective techniques for assessing candidates’ technical abilities, while also providing candidates with valuable tips for acing their interviews. 

Skip ahead to a section of the guide here:

What is a technical interview?

A technical interview is a method employed by recruiters to evaluate candidates for software engineering and other technical roles. Technical interviews often focus on assessing a candidate’s job-relevant technical skills, problem-solving abilities, and communication style. The insights gathered from these interviews should help employers decide how successful a candidate would be in the role they’re applying for.

What are the different stages of technical interviews?

The different stages hiring for technical roles may vary depending on the company and engineering role, but usually, technical interviews can be broken down into the following stages:

Initial screening and assessment

Companies often begin the hiring process for technical roles with pre-screen assessments to hone in on qualified candidates. By incorporating these preliminary evaluations, employers can efficiently narrow down the applicant pool to a more manageable number of well-suited candidates early in the hiring process. Pre-screen assessments not only save time and resources for the hiring team, but also ensure that the candidates advancing to the next stages possess the necessary expertise and aptitude for the role. They are generally preferred to resume review as a method for initial screening candidates for technical roles.

CodeSignal Pre-Screen is a powerful tool for assessing engineering candidates at the top of the recruiting funnel. With Pre-Screen, companies can effectively streamline the initial evaluation process with objective and validated skills assessments. Since Pre-Screen Certified Evaluations are developed, validated, and maintained by CodeSignal, engineering teams reduce the amount of time they spend on recruiting by thousands of hours per year. Furthermore, Pre-Screen helps minimize bias in the hiring process, as it emphasizes objective metrics and skill-based evaluations rather than relying on factors such as educational background or previous work experience. 

Behavioral interview

The behavioral interview stage of the engineering hiring process focuses on evaluating a candidate’s soft skills, interpersonal abilities, and overall fit within the company culture. Unlike the technical interview, which assesses the candidate’s coding skills and other problem-solving abilities, the behavioral interview delves into their past experiences, work habits, and personality traits. Interviewers often pose situational or hypothetical questions to gauge the candidate’s ability to handle challenges, work effectively within a team, and adapt to an organization’s values and expectations. 

Technical interview

During the technical interview stage of the engineering hiring process, candidates are generally asked to showcase their coding abilities in real-time using an integrated development environment (IDE). This stage is a crucial opportunity for both the candidate and the engineering hiring manager to gain a deeper understanding of each other’s working style and thought processes. In this scenario, the candidate typically works on a coding problem or a small project while the hiring manager observes and assesses their problem-solving skills, technical knowledge, and overall approach. The collaborative nature of the exercise allows the hiring manager to ask clarifying questions, gauge the candidate’s communication skills, and evaluate their ability to adapt under pressure. Solutions like CodeSignal Pre-Screen provide a research-backed technical screening solution to significantly reduce the burden of technical interviewing on engineering teams.

On-site interview

The on-site interview stage is the final step in the engineering hiring process, designed to provide a comprehensive evaluation of the candidate’s technical and communication skills. Conducted by a panel of engineers, this stage typically involves a live coding exercise in which the candidate is tasked with solving complex problems or working on a project relevant to the role. The panel assesses the candidate’s problem-solving approach, coding proficiency, and ability to think on their feet. 

Additionally, the on-site interview allows the panel to observe the candidate’s communication and collaboration skills, as they may be required to discuss their thought process, ask questions, or seek feedback from the panel members. This immersive, interactive experience offers valuable insights into the candidate’s potential fit within the team and their capacity to excel in the engineering role. CodeSignal Interview is a live interviewing tool designed for on-site and panel interviews and provides a realistic development environment with built-in video calling for interviewers to evaluate candidates’ job-relevant skills.

Post-interview debrief

The final interview debrief is a crucial step in the engineering hiring process, as it allows the interviewers to come together and thoroughly discuss the candidate’s performance throughout the various stages of the evaluation. In order to objectively assess the candidate’s job-relevant skills, interviewers often employ a numerical rubric, assigning scores based on predefined criteria, such as technical expertise, problem-solving abilities, and collaboration skills By utilizing this consistent method of evaluation, the hiring team can compare candidates more accurately, ensuring that the final decision is rooted in objective data rather than subjective opinions. 

What are the different formats of technical interviews?

Online coding assessment

An online coding assessment is a standardized evaluation tool used by employers to gauge a candidate’s programming skills and other problem-solving abilities during the technical hiring process. These assessments typically consist of coding challenges or exercises that require candidates to write, analyze, and debug code. Online coding assessments also streamline the hiring process, allowing companies to efficiently filter potential candidates and identify top talent for their technical teams.

Multiple choice quiz

A multiple-choice quiz for technical hiring is an evaluation method used to assess a candidate’s knowledge of specific programming languages, frameworks, or concepts. These quizzes typically present a series of questions or problem statements, requiring the candidate to select the correct answer from a list of options. Although multiple-choice quizzes can provide a quick and straightforward way to gauge a candidate’s theoretical understanding, they have limitations in accurately measuring a candidate’s practical coding skills or ability to solve complex, real-world problems. As a result, these quizzes may not provide a comprehensive view of a candidate’s capabilities, potentially leading to poorly-informed hiring decisions.

Take home assignment

A take-home assignment for technical hiring is a project-based assessment that requires candidates to complete a coding or engineering task outside of the interview setting, often simulating real-world scenarios or problems. These assignments provide valuable insights into a candidate’s problem-solving abilities, creativity, and practical skills. However, take-home assignments can be time-consuming for candidates, as they may require several hours or even days to complete. This extended time commitment can be a deterrent for highly skilled candidates with limited availability, potentially causing them to opt out of the application process or seek opportunities with a less burdensome hiring process.

Whiteboard interview

A whiteboard interview for technical hiring is a traditional evaluation method in which candidates are asked to solve coding problems or design algorithms on a whiteboard, often in front of an interviewer or panel. This approach is intended to assess a candidate’s thought process, problem-solving abilities, and communication skills. However, whiteboard interviews have notable limitations, as they can create an artificial, high-pressure environment that may not accurately reflect a candidate’s true capabilities or the day-to-day work experience (since real code isn’t written on a whiteboard). Additionally, these interviews may inadvertently favor candidates with strong presentation skills over those with stronger technical abilities but who may not perform well under such stressful conditions.

Technical interview perspectives: engineering candidate vs. interviewer

What’s the candidate’s perspective on technical interviews? 

From the software engineering candidate’s perspective, technical interviews can be both exciting and nerve-wracking. On the one hand, technical interviews provide an opportunity for candidates to showcase their coding skills, problem-solving abilities, and experience. On the other hand, the pressure to perform well and the fear of being asked a question they don’t know the answer to can be intimidating.

What’s the interviewer’s perspective on technical interviews? 

While technical interviews can be challenging for candidates, they can also be challenging for interviewers. Interviewers must be able to assess a candidate’s abilities objectively and fairly, while also providing a positive and welcoming experience for the candidate. They may need to adjust their approach based on the candidate’s experience level, communication style, or learning style.

Technical interview tips for recruiters & engineering managers

How should you conduct a technical interview?

To conduct a technical interview effectively, start by defining the specific skills and knowledge required for the position, and develop a clear evaluation criterion to assess the candidate’s abilities. Ideally, this step would involve engaging IO Psychologists in a job analysis that identifies the knowledge, skills, abilities, and other characteristics (KSAOs) required for a candidate to succeed in the role. 

A technical interview may incorporate a combination of evaluation methods, such as coding tasks and knowledge-based questions, to obtain a comprehensive understanding of the candidate’s technical capabilities, problem-solving skills, and ability to communicate complex concepts. Ideally, the interview process should be structured to minimize stress and provide a realistic representation of the candidate’s day-to-day work environment.

CodeSignal provides pre-screen assessment, full-service technical interview, and live coding interview solutions that provide an advanced, realistic integrated development environment (IDE) for candidates and interviewers. With CodeSignal Interview, for instance, interviewers can observe a candidate’s coding process in real-time, engage in collaborative problem-solving, and even pull up a candidate’s pre-screen assessment results in the coding environment. This environment provides a “flight simulator” experience for candidates while enabling interviewers to assess the candidate’s skills effectively and efficiently. 

What interviewers should look for when hiring software engineers

When hiring software engineers, interviewers should look for a combination of technical skills, problem-solving abilities, and communication skills. A strong foundation in programming languages, frameworks, and algorithms is important, and the capacity to learn and adapt to new technologies is essential. Equally important is the candidate’s ability to analyze complex problems, develop creative solutions, and collaborate effectively within a team. Finally, soft skills such as communication, time management, and resilience are crucial, as they enable the candidate to navigate challenges, articulate ideas, and contribute positively to a team’s overall success and growth.

Technical interview tips for software engineer candidates

Approaching a technical interview as a candidate can feel quite daunting, particularly if it’s been some time since you’ve taken a similar assessment. Your performance in these interviews greatly influences the hiring decision, so it’s important to prepare well. 

How to make a great impression in your technical interview as a software engineer

As a software engineer, making a great impression in your technical interview is essential for showcasing your skills and securing the job offer. To ensure success, consider the following strategies:

  • Prepare thoroughly: Brush up on your knowledge of programming languages, data structures, and algorithms, and familiarize yourself with the technologies and frameworks relevant to the job.
  • Practice problem-solving: Work through coding challenges or sample interview questions to hone your problem-solving skills and develop a structured approach to tackling complex tasks.
  • Demonstrate clear communication: Articulate your thought process while solving problems, ask clarifying questions when needed, and explain your solutions in a concise, understandable manner.
  • Showcase teamwork and adaptability: Be receptive to feedback, collaborate effectively with interviewers, and demonstrate a willingness to adapt your approach when presented with new information.
  • Show confidence and professionalism: Present yourself confidently, maintain a positive attitude, and exhibit enthusiasm for the role and the company.

How to prepare for a technical interview

1. Research the company and role

When applying for a software engineering role, it’s crucial for you to research the company and the specific position thoroughly. This research should involve understanding the company’s products, services, and overall mission. By gaining insight into the company culture, team dynamics, and tech stack, you can tailor your approach during the interview process, demonstrating a genuine interest in the organization and showcasing your ability to be a valuable contributor to the team’s success.

2. Review technical concepts and skills specific to the role

Before your first interview for a software engineering role, make sure to thoroughly review the technical concepts and skills specific to the position. This may involve refreshing your knowledge of programming languages, frameworks, or tech stack listed in the job description, and practicing relevant coding challenges or exercises.

3. Practice online coding challenges

Software engineering candidates seeking effective preparation for upcoming technical interviews should consider engaging in coding interview challenges. Regular practice with these challenges allows you to refine your problem-solving abilities, enhance your algorithmic thinking, and become acquainted with the structure of technical interview questions. Incorporating practice coding challenges into your interview preparation will boost your confidence—and performance—in technical interviews.

4. Prepare questions to ask the interviewer

Preparing questions to ask your interviewer when interviewing for a software engineering position demonstrates your interest in the role and showcases your proactive attitude. Ask insightful questions to help you better understand the company culture, team dynamics, and expectations of the role—and ensure that the position aligns with your career goals and values. For example, you might consider asking about the company’s approach to software development methodologies, or how the team handles code reviews and maintains code quality. 

What to expect during your technical Interview

As a software engineering candidate, you should be prepared for a range of topics and coding challenges during your technical interview. These interviews typically assess your coding skills, problem-solving abilities, and understanding of computer science fundamentals: algorithms, frameworks, data structures, and more. 

You may be asked to write code on a whiteboard or in an online coding environment, solve algorithmic puzzles, or discuss architectural design principles. The interviewer might also delve into your past experiences, asking you to explain your thought process or approach to specific projects. Remember: the primary goal of the technical interview is to evaluate not just your technical proficiency, but also your ability to communicate and collaborate effectively with others. Keep a positive attitude, demonstrate your thought process, and don’t be afraid to ask clarifying questions if needed. 

Examples of technical interview questions & answers

It’s impossible to provide an exhaustive list of interview questions you might encounter as part of this guide. The type of questions will vary depending on the role, technologies, and the type of position that you are interviewing for. Nevertheless, here are a few examples of the types of questions you might encounter.

Question: How would you reverse a string in your preferred programming language?

Acceptable answer: In Python, you can reverse a string using slicing notation with the following code:

reversed_string = original_string[::-1]

Alternatively, you can use the built-in reversed() function and join the characters:

reversed_string = ''.join(reversed(original_string))

Question: What is the difference between a stack and a queue data structure?

Acceptable answer: A stack is a last-in, first-out (LIFO) data structure, meaning the last element added is the first one to be removed. It supports two main operations: push (add an element) and pop (remove the most recently added element). A common example of a stack is a pile of plates; you add and remove plates from the top.

A queue, on the other hand, is a first-in, first-out (FIFO) data structure, meaning the first element added is the first one to be removed. It supports two main operations: enqueue (add an element to the end) and dequeue (remove the element from the front). A real-life example of a queue is a line of people waiting in a queue; people join at the end and leave from the front.

Technical interview do’s and don’ts

Technical Interview “Do’s”:

  • Review computer science fundamentals, such as data structures, algorithms, and frameworks.
  • Practice solving coding problems on various online platforms and in different programming languages.
  • Clearly communicate your thought process and problem-solving approach throughout the interview.
  • Ask clarifying questions if you’re unsure about the task or requirements.
  • Manage your time effectively, focusing on the most important aspects of the task.
  • Be prepared to discuss your past experiences and projects, emphasizing your role and contributions.
  • Demonstrate your ability to work collaboratively by being receptive to feedback and suggestions.
  • Research the company and its culture to show genuine interest and ask insightful questions.

Technical Interview “Don’ts”:

  • Avoid memorizing specific solutions or code snippets, as interviewers may use different questions in your interview.
  • Don’t underestimate the importance of soft skills, such as communication and teamwork.
  • Don’t be afraid to admit when you don’t know something. Honesty is better than bluffing.
  • Refrain from being defensive or argumentative if the interviewer challenges your solution.
  • Don’t rush through the problem. Instead, take your time to understand the requirements and constraints.
  • Avoid getting stuck on minor details or syntax. Focus on the core logic and problem-solving.
  • Don’t let nerves or anxiety overshadow your abilities. Stay calm and composed throughout the interview.
  • Refrain from giving generic answers to questions about the company or your motivation for applying.

Common technical interview scenarios and how to handle them

For candidates

Scenario 1: The interviewer asks a technical question you don’t know the answer to

You may encounter technical questions during an interview that you don’t know the answer to—it happens. In these situations, it’s crucial to remain calm and composed. Rather than trying to bluff your way through, be honest about your lack of knowledge, and express your willingness to learn. You can demonstrate your problem-solving abilities by attempting to reason through the question, discussing your thought process, and acknowledging any gaps in your understanding. If possible, relate the unknown topic to something you are familiar with, showing that you can adapt and leverage your existing knowledge. Interviewers appreciate candidates who can handle uncertainty gracefully and exhibit curiosity, humility, and a growth mindset in the face of challenges.

Scenario 2: You finish the coding challenge early and have extra time

If you complete a coding challenge during a technical interview ahead of schedule, it’s important to use the extra time wisely. First, double-check your solution for correctness, edge cases, and potential optimizations. This demonstrates your attention to detail and thoroughness. Next, consider the readability and maintainability of your code. Ensure that your code is well-structured, uses meaningful variable names, and includes comments where necessary to clarify complex logic. If appropriate, discuss alternative approaches or trade-offs with the interviewer, showcasing your depth of understanding and ability to evaluate different solutions. Finally, be prepared to answer any follow-up questions from the interviewer, as they may want to probe your knowledge or challenge your assumptions. Using your extra time effectively demonstrates your commitment to excellence and sets you apart as a strong candidate.

For interviewers

Scenario 1: Candidate struggles with a coding challenge

As an interviewer, when you notice a candidate struggling with a coding challenge, you may choose to provide guidance and support without giving away the solution. Start by encouraging the candidate to verbalize their thought process and ask clarifying questions, as this can help identify misunderstandings or gaps in their approach. Offer gentle hints or suggest breaking the problem into smaller, more manageable parts. Remember to maintain a positive and empathetic demeanor, as it can help alleviate anxiety and create a more conducive environment for the candidate to showcase their problem-solving abilities. If the candidate continues to struggle, consider modifying the question’s difficulty or shifting the focus to another aspect of the challenge that aligns better with their skillset. Regardless of your approach, be sure to offer consistent support for each candidate to prevent unfairness or bias in your hiring process.

Scenario 2: Candidate is overconfident

If a candidate seems overconfident or dismissive of feedback, try gently challenging their assumptions and providing constructive criticism. Ask follow-up questions to clarify their thought process and provide feedback on areas where they could improve. It’s important to balance this with positive feedback and encouragement so the candidate doesn’t become discouraged.

Final thoughts

This guide to technical interviews has provided comprehensive documentation of what technical interviews are, as well as different types and formats of technical interviews. It has also offered guidance to interviewers on how best to assess candidates’ job-relevant skills, and advice for candidates on how to prepare for a technical interview, what to expect during the interview, and how best to handle challenges that arise. For technical interviews that help companies identify and secure a “yes” from their top candidates, hundreds of companies turn to CodeSignal.

Want to learn more about how CodeSignal can elevate your technical interviews and help you make the right hires, faster? Schedule a call with one of our tech hiring experts.