Klarna Software Engineer Interview Questions + Guide in 2025

Klarna is a leading fintech company aiming to revolutionize the shopping experience for consumers and merchants alike, with over 150 million active users and 2 million transactions per day.

As a Software Engineer at Klarna, you will be tasked with developing and maintaining software solutions that enhance the company's operations and improve customer experiences. Key responsibilities include designing and implementing automated systems for operational risk management, developing features for Klarna's payment solutions, and collaborating with cross-functional teams to ensure cohesive product development. You will work extensively with programming languages such as Python and SQL, and may engage in projects involving machine learning and data analysis. A strong grasp of system architecture, coding best practices, and problem-solving skills are essential, as is the ability to work in a fast-paced and evolving environment. Klarna values innovation, collaboration, and a customer-centric approach, so candidates who demonstrate adaptability, creativity, and a commitment to delivering high-quality solutions will thrive in this role.

This guide aims to equip you with the insights and knowledge necessary to effectively prepare for your interview at Klarna, helping you to highlight your skills and experiences that align with the company’s mission and values.

The interview process for a Software Engineer at Klarna is known for its length and complexity, often involving multiple stages that assess both technical skills and cultural fit. Here’s a breakdown of the typical steps you can expect:

1. Initial Screening

The process begins with an initial screening call with a recruiter. This conversation typically lasts around 30 minutes and focuses on your background, motivations for applying, and basic behavioral questions. The recruiter will also provide an overview of the role and the company culture, setting the stage for the subsequent steps.

2. Coding Challenge

Following the initial screening, candidates are usually required to complete a coding challenge. This is often conducted online and may consist of several algorithmic problems that test your coding skills. You may be given a set time to complete the challenge or allowed to work on it at your own pace, depending on the specific requirements of the role.

3. Logic and IQ Test

Candidates may also be asked to take a logic or IQ test, which is typically administered in a video call format. This test assesses your problem-solving abilities and logical reasoning skills, often involving pattern recognition or other cognitive tasks.

4. Technical Interviews

If you pass the initial tests, you will move on to a series of technical interviews. These interviews can vary in format but generally include: - Live Coding Session: You will be asked to solve coding problems in real-time, often using a shared coding environment. Interviewers may ask you to explain your thought process as you work through the problems. - System Design Interview: This interview focuses on your ability to design scalable systems. You may be asked to discuss architectural decisions and how you would approach building a system from the ground up. - Behavioral Interview: This part of the process assesses your alignment with Klarna's leadership principles and company culture. Expect questions that require you to reflect on past experiences and how they relate to teamwork, conflict resolution, and project management.

5. Final Interviews

The final stage typically involves meeting with senior engineers or team leads. This may include additional technical assessments or discussions about your fit within the team. You might also have a chance to meet potential colleagues and get a sense of the team dynamics.

6. Offer and Feedback

After completing all interview stages, candidates will receive feedback on their performance. If successful, you will be presented with a job offer. However, it’s worth noting that feedback can sometimes be delayed, and candidates may experience a lack of communication throughout the process.

As you prepare for your interview, it’s essential to be ready for a variety of questions that reflect both your technical expertise and your understanding of Klarna's values and operations.

Here are some tips to help you excel in your interview.

Understand the Interview Process

Klarna's interview process can be lengthy and may involve multiple stages, including coding challenges, logic tests, and behavioral interviews. Familiarize yourself with the typical structure, which often includes an initial HR screening, followed by technical assessments and interviews focused on cultural fit and leadership principles. Being prepared for a potentially drawn-out process will help you manage your expectations and reduce stress.

Prepare for Technical Assessments

Expect to encounter a variety of technical challenges, including coding assignments and system design interviews. Brush up on your coding skills, particularly in languages relevant to the role, such as Python or JavaScript. Practice common algorithmic problems and familiarize yourself with system design concepts. Given the feedback from candidates, be ready for hands-on coding exercises that may require you to think out loud and explain your thought process.

Emphasize Klarna's Leadership Principles

Klarna places a strong emphasis on its leadership principles during interviews. Be prepared to discuss how your experiences align with these values. Reflect on past situations where you demonstrated qualities such as collaboration, innovation, and accountability. Use the STAR (Situation, Task, Action, Result) method to structure your responses, ensuring you convey your thought process and the impact of your actions.

Communicate Clearly and Confidently

Effective communication is key during interviews at Klarna. Be clear and concise in your responses, especially when discussing technical concepts or your past experiences. Practice articulating your thoughts and solutions, as interviewers may appreciate candidates who can explain complex ideas in an understandable manner. Additionally, be prepared to ask insightful questions about the team and the company to demonstrate your interest and engagement.

Manage Your Time and Expectations

Given the feedback from candidates about the lengthy and sometimes disorganized interview process, it's important to manage your time and expectations. If you encounter delays or lack of communication, remain patient and professional. Follow up politely if you haven't received feedback within the expected timeframe, but also be prepared for the possibility of a drawn-out process.

Stay Positive and Resilient

The interview experience at Klarna can be challenging, with reports of frustration regarding the recruitment process. Maintain a positive attitude throughout your interactions, regardless of any setbacks. Show resilience and adaptability, as these traits are valuable in a fast-paced environment like Klarna. Remember that every interview is an opportunity to learn and grow, regardless of the outcome.

By following these tips and preparing thoroughly, you can enhance your chances of success in the interview process at Klarna. Good luck!

In this section, we’ll review the various interview questions that might be asked during a software engineering interview at Klarna. The interview process is known to be extensive and may include a variety of technical and behavioral assessments. Candidates should be prepared to demonstrate their coding skills, system design knowledge, and alignment with Klarna's leadership principles.

Coding and Algorithms

1. Can you explain the difference between a stack and a queue?

Understanding data structures is fundamental for any software engineer. Be prepared to discuss their properties and use cases.

How to Answer

Explain the key differences, such as how stacks are LIFO (Last In, First Out) and queues are FIFO (First In, First Out). Provide examples of when you would use each structure.

Example

“A stack is a data structure that follows the LIFO principle, meaning the last element added is the first to be removed. This is useful in scenarios like function call management in programming. In contrast, a queue follows the FIFO principle, where the first element added is the first to be removed, which is ideal for scenarios like task scheduling.”

2. Describe a coding challenge you faced and how you solved it.

This question assesses your problem-solving skills and ability to articulate your thought process.

How to Answer

Choose a specific challenge, describe the problem, your approach to solving it, and the outcome. Highlight any tools or languages you used.

Example

“I once faced a challenge where I had to optimize a search algorithm that was running too slowly. I analyzed the time complexity and realized I could implement a binary search instead of a linear search, which reduced the time from O(n) to O(log n). This significantly improved the performance of the application.”

3. How do you approach debugging a piece of code?

Debugging is a critical skill for software engineers, and your approach can reveal your analytical thinking.

How to Answer

Discuss your systematic approach to identifying and fixing bugs, including tools you use and how you test your solutions.

Example

“When debugging, I first try to reproduce the issue consistently. Then, I use print statements or a debugger to trace the flow of execution and identify where things go wrong. Once I find the root cause, I implement a fix and run tests to ensure the issue is resolved without introducing new bugs.”

4. What is your experience with version control systems?

Version control is essential in collaborative software development environments.

How to Answer

Discuss your familiarity with systems like Git, including branching strategies and how you handle merge conflicts.

Example

“I have extensive experience using Git for version control. I typically follow a feature branching strategy, where I create a new branch for each feature or bug fix. When merging, I ensure to resolve any conflicts by discussing with team members to understand the best approach.”

5. Can you explain a time when you had to optimize an existing codebase?

This question evaluates your ability to improve code efficiency and maintainability.

How to Answer

Provide a specific example where you identified inefficiencies and the steps you took to optimize the code.

Example

“In a previous project, I noticed that a data processing function was taking too long to execute due to nested loops. I refactored the code to use a more efficient algorithm and implemented caching for repeated calculations, which reduced the processing time by over 50%.”

System Design

1. How would you design a scalable API?

This question tests your understanding of system architecture and scalability.

How to Answer

Discuss the principles of designing APIs, including RESTful design, statelessness, and how you would handle scaling.

Example

“I would start by defining the resources and endpoints needed for the API, ensuring it follows RESTful principles. To handle scalability, I would implement load balancing and consider using microservices architecture. Additionally, I would use caching strategies to reduce database load and improve response times.”

2. Describe how you would approach a system design interview.

This question assesses your thought process and ability to communicate your design choices.

How to Answer

Outline your approach, including gathering requirements, defining components, and considering trade-offs.

Example

“I would begin by clarifying the requirements and constraints of the system. Then, I would sketch out the high-level architecture, identifying key components and their interactions. I would also consider scalability, reliability, and security aspects, discussing trade-offs where necessary.”

3. What considerations would you take into account when designing a database schema?

Database design is crucial for data integrity and performance.

How to Answer

Discuss normalization, indexing, and how you would handle relationships between entities.

Example

“When designing a database schema, I would focus on normalization to reduce redundancy while ensuring data integrity. I would also consider indexing on frequently queried fields to improve performance. Additionally, I would define relationships between tables carefully to maintain referential integrity.”

4. How do you ensure the security of an application you are developing?

Security is a critical aspect of software development.

How to Answer

Discuss best practices for securing applications, including authentication, authorization, and data protection.

Example

“I ensure application security by implementing strong authentication mechanisms, such as OAuth or JWT for API access. I also validate and sanitize user inputs to prevent SQL injection and XSS attacks. Regular security audits and keeping dependencies up to date are also part of my approach.”

5. Can you walk me through a project where you had to integrate multiple systems?

This question evaluates your experience with system integration and collaboration.

How to Answer

Describe the project, the systems involved, and how you managed the integration process.

Example

“In a recent project, I integrated a payment gateway with our e-commerce platform. I coordinated with both teams to understand their APIs and data formats. I implemented a middleware service to handle data transformation and ensure smooth communication between the systems, which resulted in a seamless user experience.”

Behavioral Questions

1. Tell me about a time you had to work under pressure.

This question assesses your ability to handle stress and meet deadlines.

How to Answer

Choose a specific instance, describe the situation, your actions, and the outcome.

Example

“During a critical project, we faced a tight deadline due to unexpected changes in requirements. I organized daily stand-up meetings to track progress and address blockers. By prioritizing tasks and collaborating closely with my team, we successfully delivered the project on time.”

2. How do you handle conflicts within a team?

Conflict resolution is essential for maintaining a productive work environment.

How to Answer

Discuss your approach to resolving conflicts, emphasizing communication and collaboration.

Example

“When conflicts arise, I believe in addressing them directly and openly. I encourage team members to express their viewpoints and facilitate a discussion to find common ground. By focusing on the project goals and fostering a collaborative atmosphere, we can often resolve conflicts amicably.”

3. Describe a time when you had to adapt to a significant change at work.

This question evaluates your flexibility and adaptability.

How to Answer

Provide an example of a change you faced, how you adapted, and the impact it had.

Example

“When our team transitioned to a new project management tool, I took the initiative to learn it quickly and help my colleagues adapt. I organized training sessions and created documentation to ease the transition. This proactive approach helped the team become comfortable with the new tool and improved our workflow.”

4. What motivates you in your work?

Understanding your motivation can help assess cultural fit.

How to Answer

Discuss what drives you, whether it’s problem-solving, collaboration, or achieving goals.

Example

“I am motivated by the challenge of solving complex problems and the opportunity to learn new technologies. I find great satisfaction in delivering high-quality software that positively impacts users and contributes to the team’s success.”

5. How do you prioritize your tasks when working on multiple projects?

This question assesses your time management and organizational skills.

How to Answer

Discuss your approach to prioritization, including tools or methods you use.

Example

“I prioritize tasks based on urgency and impact. I use tools like Trello to visualize my workload and set deadlines. I also communicate with my team to ensure alignment on priorities and adjust as needed based on project requirements.”