Finding the perfect fit: essential software engineer interview questions
September 22, 2023
min read

Finding the perfect fit: essential software engineer interview questions

Luis Minvielle
Luis Minvielle

Almost every sector, from finance to Big Tech, seeks software developers to hike up their gains. Recruiters and HR are at the forefront, linking businesses with these professionals, ensuring both technical capability and a cultural match. 

Interview questions that poke at this cultural match and capability while also spiking the interest of sought-after developers might give the edge to an HR team. 

This post focuses on vital software engineer interview questions to help recruiters pinpoint top candidates. By posing the right inquiries and carefully evaluating answers, they can significantly influence a company's future success.

1. Preparing for the interview process

A well-structured interview process is crucial for effectively evaluating software engineering candidates. Before conducting interviews, it’s essential to define specific job requirements and align them with the company’s culture. This ensures that the selected candidates not only possess the required technical skills but also fit perfectly within the organisation’s values and working environment.

To maintain consistency and fairness, companies should develop a standardised interview structure with a consistent set of questions and evaluation criteria. Utilising multiple interview formats, such as technical screenings, behavioural interviews, and coding exercises, offers a more comprehensive assessment of candidates’ abilities. With meetings becoming increasingly short, companies could set for a highly-curated low number of questions, trying to make their interview last half an hour ideally.


Providing timely and constructive feedback to candidates further enhances the overall candidate experience, regardless of the hiring outcome, and positively reflects the company’s employer brand. By adhering to these practices, recruiters can attract top software engineering talent and build a highly productive team.

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2. Technical screening questions

Technical screening questions are a critical component of the software engineer interview process, as they enable recruiters and HR professionals to assess a candidate’s fundamental knowledge and skills in various technical areas. These questions go beyond the resume and provide valuable insights into a candidate’s ability to apply their knowledge to real-world scenarios, problem-solving capabilities, and suitability for the role.

Technical screening questions help recruiters identify candidates with the necessary expertise to excel in the software engineering role. By evaluating a candidate’s grasp of programming languages, algorithms, data structures, and problem-solving techniques, recruiters can gauge their technical proficiency and potential to contribute meaningfully to the team. Additionally, these questions serve as a filter to ensure that only candidates with the required technical foundation proceed to the next stages of the interview process, saving both the candidate’s and the company’s time and resources.

Sample technical screening questions:

1. Programming languages

  • Can you tell us about your favourite programming language and why it appeals to you? How do you think its unique features contribute to software development?
  • Have you explored any unconventional or emerging programming languages? What intrigued you about them, and how do you see them influencing the future of software engineering?

2. Algorithms

  • Share a challenging problem you encountered in the past and how you approached solving it using algorithms. What valuable lessons did you learn from that experience?
  • Discuss a scenario where you had to optimise an algorithm for better performance or efficiency. How did you approach the optimisation process, and what were the outcomes?

3. Data structures

  • When designing a system, what factors do you consider when selecting the appropriate data structure? Can you provide an example of how the choice of data structure impacted the overall system’s performance and scalability?
  • Reflecting on your past projects, share a situation where the selection of a specific data structure was pivotal in achieving the desired functionality or improving the user experience.

3. Behavioural and soft skills questions

The adage states that people in STEM fields can tackle intricate mathematical problems, but they could call in sick if they realise they must engage in a 15-second chat on the elevator leading to the office’s cafeteria.

Will the candidate be as shy as the myth tells? Or is it just unsupported gossip? HR professionals should take this into account. Evaluating behavioural and soft skills alongside technical proficiency is crucial in the software engineer interview process. While technical skills are essential for performing the job, behavioural and soft skills are vital in determining how well a candidate fits within the team and contributes to a positive and productive work environment.

Software engineers do not work isolated; they collaborate with team members, communicate ideas, and solve complex problems together. Assessing behavioural and soft skills helps recruiters gauge a candidate’s ability to work effectively in a team, communicate clearly and concisely, adapt to changing circumstances, and approach problem-solving with creativity and efficiency. A candidate with solid behavioural and soft skills is more likely to thrive in a collaborative setting, foster constructive interactions, and contribute positively to the team’s dynamics, ultimately enhancing the overall productivity and success of the software development process.

Sample behavioural and soft skills questions:

1. Communication

  • Describe a situation where you had to explain a complex technical concept to a non-technical audience. How did you ensure effective communication?
  • How do you handle disagreements or conflicts within a team, and how do you promote open communication?

2. Teamwork

  • Can you share an experience where you collaborated with colleagues from different departments to achieve a common goal? How did you contribute to the team’s success?
  • How do you approach teamwork with diverse perspectives and skill sets? 

3. Adaptability

  • Describe a project where you had to adapt to changing requirements or tight deadlines. How did you manage the situation, and what did you learn from it?
  • How do you stay updated with the latest technological advancements and best practices in the software engineering field?

4. System design and architecture questions

Understanding a candidate’s ability to design scalable and efficient software systems is paramount in the software engineer interview process. System design and architecture play a critical role in shaping the performance, reliability, and maintainability of applications. Evaluating a candidate’s skills in this area ensures that they can handle complex projects, anticipate future growth, and create robust solutions that align with the company’s long-term objectives.

Software systems in modern tech environments often deal with a massive influx of data and users. It is crucial to have software engineers who can envision and implement scalable architectures to handle increasing demands. By assessing a candidate’s system design and architectural skills, recruiters can gauge their ability to break down complex problems into modular components, choose appropriate technologies, and devise efficient data storage and retrieval strategies. Strong system design skills contribute to building software that is not only high-performing but also easily maintainable and adaptable to future changes and expansions.

Sample system design and architecture questions:

1. Scalable web application design

  • You are tasked with designing a web application to handle a rapidly growing user base. How would you structure the system to ensure it can accommodate thousands of concurrent users while maintaining responsiveness?

2. Database architecture

  • You must design the database schema for an e-commerce platform with millions of products and users. What database structure would you pick to optimise data retrieval performance and ensure data consistency?

3. Microservices vs. monolithic architecture

  • Discuss the benefits and drawbacks of microservices and monolithic architecture, and in what scenarios would you recommend using each?

4. API Design

  • You are designing an API for a mobile application that interacts with various backend services. How would you structure the API endpoints to optimise efficiency and minimise API call overhead?

5. Coding exercises and pair programming

Coding exercises and pair programming sessions are invaluable tools in evaluating a candidate’s coding abilities and collaboration skills during the software engineer interview process. These interactive and hands-on methods provide more profound insights into a candidate’s technical proficiency, problem-solving approach, and ability to work effectively with others in a team-based environment.

Through coding exercises, recruiters can make real-time assessments of candidates' coding skills, observing their problem-solving approaches and ability to handle complex scenarios. These exercises serve as challenging platforms, prompting candidates to think critically and creatively, arriving at optimal solutions within a limited timeframe. 

Moreover, pair programming sessions enable the evaluation of collaboration skills, as candidates work as a team, providing feedback, and considering alternative viewpoints during the development process. Additionally, candidates engaging in coding exercises and pair programming must demonstrate adaptability and effective communication, thinking on their feet and explaining their thought process with clarity and coherence.

Some cautions:

  • If you’re doing this remotely, your candidate will probably have Stack Overflow holding off in the background, ready to bring up the answer immediately.
  • Some well-available AIs are pretty good at solving exercises as well. Candidates could be relying on these tools to sort the puzzle out promptly.
  • Not every programming role would require the same activity. A frontend developer will have different technical capabilities than a backend one, and the exercise should cater to the position. If not, it might even get frustrating for the candidate. An HR professional wouldn’t want to be requested to write an essay in French if the role requires only English and German, for example.

Some recommendations:

  • It could be a good idea to directly ask the reporting manager about what technical exercises they would want a candidate to solve. They will know which tech scope to tackle, which stack to evaluate, and, more importantly, what kind of answer they should be waiting for. 
  • Maybe the manager actually embraces AI — and wants to check how the candidate harnesses it.

Suggested coding exercises and activities

1. Algorithmic challenges

  • Provide candidates with algorithmic problems to solve, such as sorting algorithms, searching algorithms, or graph-related problems.

2. Data structure implementations:

  • Ask candidates to implement common data structures like linked lists, stacks, queues, or binary trees.

3. Web development tasks

  • For front-end or full-stack positions, assign tasks like building a simple web page using HTML, CSS, and JavaScript.

4. Database queries

  • Present candidates with scenarios where they need to write SQL queries to retrieve or manipulate data from a database.

5. Code review and refactoring

  • Provide a code snippet and ask candidates to review it for potential bugs or improvements. Alternatively, ask them to refactor the code to enhance its efficiency or readability.

6. API integration

  • For backend or full stack roles, have candidates integrate with an external API and perform specific operations.

7. Pair programming session

  • Conduct a collaborative coding session where the candidate works with an interviewer on a small project or a specific coding task.

8. Debugging challenges

  • Present candidates with code snippets containing bugs and assess their ability to identify and fix the issues.

6. A candidate’s willingness to learn

The very next topmost programming language or fashionable project might not exist now — but could drop three months from now. As many technologies become obsolete and others come in to reign in their stead, HR teams could focus on figuring out if the candidate is prone — and glad — to learn. Hiring learners — instead of just experts — might give a company the edge in the following years, and HR professionals can rely on sets of questions to measure a candidate’s learning aptitudes.

Suggested questions

9. Learning anything in their leisure time

  • Have you enjoyed a newfound hobby in the last year or so, especially since the pandemic came about?

10. Having a good time picking up skills — without explicitly mentioning learning

  • What was the last time you recall having a good time getting word about something new?

7. Questions from the candidate

Facilitating the interviewee's ability to ask questions is crucial. This reveals their enthusiasm about the organisation and the position they are applying for. When candidates show interest in the company's culture, technology, growth potential, and long-term goal, it's a good sign that they'll be an excellent fit and enthusiastic about making a positive impact. Regardless of the outcome of the hiring process, both the company and the candidate benefit by paying attention to the applicant's level of interest. The HR team could even earn a good rep as a listening, employee-centric team, luring in more candidates the applicant calls out to.

Partnering up to make your questions heard

To hire the right software engineers, it's essential to view the process from all angles. An inclusive interview, where candidates can ask questions, can offer more in-depth insights into their alignment with your organisation's culture. The essential software engineer interview questions might be more of a conversation starter than a monologue.

But once you have all the great questions lined up, where should you spotlight your job description? A community like WeAreDevelopers can help you reach out to a quality audience, connecting you directly with Europe's top tech talent. 

Dive deeper into our blog to learn more, or schedule a chat with our team for a hands-on approach.


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