Extend Data Engineer Interview Questions + Guide in 2025

Extend is a rapidly growing fintech startup focused on innovating the B2B payments space through the development of virtual card platforms.

As a Data Engineer at Extend, you will play a critical role in building and optimizing the data architecture that drives the company's operations. Your key responsibilities will include designing and maintaining scalable database systems, implementing data pipelines, and ensuring efficient data flow across various platforms. You will work closely with cross-functional teams to support data-driven decision-making processes, so strong collaboration skills are essential. Given Extend's commitment to performance and accessibility, candidates should have a solid understanding of system design principles and a proven ability to optimize core data infrastructure.

Ideal candidates will bring 7-10 years of experience in backend development with a focus on data engineering, along with expertise in AWS infrastructure, data modeling, and CI/CD pipelines. Attributes such as strong analytical reasoning, effective communication skills, and a proactive approach to problem-solving are highly valued in this role. An understanding of the fintech landscape will further enhance your fit within Extend’s mission-driven culture.

This guide is crafted to help you navigate the interview process effectively, equipping you with the insights and knowledge to showcase your qualifications and align with Extend's values.

The interview process for a Data Engineer at Extend is designed to assess both technical skills and cultural fit within the rapidly growing fintech environment. The process typically unfolds as follows:

1. Initial Screening

The first step involves a brief phone call with a recruiter. This conversation focuses on your resume, professional background, and motivations for applying to Extend. The recruiter will gauge your alignment with the company culture and discuss the role's expectations.

2. Hiring Manager Interview

Following the initial screening, candidates will have a one-on-one interview with the hiring manager. This session delves deeper into your technical expertise, particularly in data engineering and backend development. Expect discussions around your experience with data architecture, system design, and problem-solving capabilities. The hiring manager will also assess your fit within the team and the broader company culture.

3. Technical Interviews

Candidates will then participate in multiple technical interviews, typically conducted via video conferencing. These interviews may involve discussions with various team members, including both frontline and senior leadership. The focus will be on your ability to solve real-world problems, particularly those related to data infrastructure and system design. You may be asked to demonstrate your knowledge of AWS, data modeling, and CI/CD practices.

4. Case Study Presentation

A unique aspect of the interview process at Extend is the requirement to present a case study. Candidates will be given a take-home assignment that reflects the type of data challenges they would encounter in the role. This presentation allows you to showcase your analytical reasoning, problem-solving skills, and ability to communicate complex ideas effectively.

5. Final Interviews

The final stage typically includes interviews with cross-functional team members. These sessions may cover behavioral questions and further technical assessments. The goal is to ensure that you can collaborate effectively with various stakeholders and contribute to the company's data-driven decision-making processes.

As you prepare for your interviews, it's essential to be ready for a mix of technical and behavioral questions that reflect the skills and experiences relevant to the Data Engineer role at Extend.

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

Understand the Interview Structure

The interview process at Extend typically involves multiple stages, including an initial screening with HR, followed by interviews with the hiring manager and team members. Be prepared for a case study presentation, as this is a common component. Familiarize yourself with the structure so you can anticipate what’s next and prepare accordingly.

Showcase Problem-Solving Skills

Expect to encounter questions that assess your ability to solve problems through coding and system design. Focus on demonstrating your thought process and how you approach challenges. Be ready to discuss specific examples from your past experiences where you successfully tackled complex data engineering problems.

Emphasize Cultural Fit

Extend values a collaborative and transparent work environment. During your interviews, highlight your ability to work effectively in teams and your alignment with the company’s mission-driven culture. Share experiences that showcase your adaptability and how you thrive in fast-paced, startup settings.

Prepare for Technical Assessments

While some candidates reported a lack of technical questions, it’s wise to be prepared for them. Brush up on your knowledge of data architecture, AWS infrastructure, and data modeling principles. Be ready to discuss your experience with relevant technologies like PostgreSQL, DBT, and RabbitMQ, as well as your approach to building scalable data solutions.

Ask Insightful Questions

Interviews are a two-way street. Prepare thoughtful questions that demonstrate your interest in the role and the company. Inquire about the team dynamics, the challenges they face in data engineering, and how they measure success. This not only shows your enthusiasm but also helps you gauge if Extend is the right fit for you.

Be Ready for Behavioral Questions

Expect behavioral questions that explore your past experiences and how you handle various situations. Use the STAR (Situation, Task, Action, Result) method to structure your responses, ensuring you provide clear and concise examples that highlight your skills and contributions.

Manage Your Time Wisely

Given the multi-step interview process, time management is crucial. Allocate sufficient time for each stage, especially for the take-home assignments, which can be extensive. Don’t hesitate to ask for clarification on expectations or deadlines to ensure you deliver your best work.

Stay Positive and Engaged

Throughout the interview process, maintain a positive demeanor and engage with your interviewers. Even if you encounter challenging questions or situations, approach them with a constructive attitude. This will leave a lasting impression and demonstrate your resilience and professionalism.

By following these tips, you’ll be well-prepared to navigate the interview process at Extend and showcase your qualifications as a Data Engineer. Good luck!

In this section, we’ll review the various interview questions that might be asked during a Data Engineer interview at Extend. The interview process will likely focus on your technical skills, problem-solving abilities, and cultural fit within the company. Be prepared to discuss your experience with data architecture, system design, and your approach to collaboration in a fast-paced environment.

Technical Skills

1. Can you describe your experience with AWS and how you have utilized it in your previous projects?

Understanding your familiarity with AWS is crucial, as it is a key component of Extend's tech stack.

How to Answer

Discuss specific AWS services you have used, how you implemented them, and the impact they had on your projects.

Example

“I have extensive experience with AWS, particularly with RDS and Aurora for database management. In my last project, I migrated our on-premise database to AWS, which improved our data retrieval times by 30% and significantly reduced operational costs.”

2. How do you approach designing a scalable data pipeline?

This question assesses your ability to create efficient data flows that can handle growth.

How to Answer

Explain your design principles, tools you prefer, and any challenges you’ve faced in scaling data pipelines.

Example

“I start by identifying the data sources and the expected volume of data. I use tools like Apache Kafka for real-time data ingestion and AWS Glue for ETL processes. In a previous role, I designed a pipeline that scaled from processing 1TB to 10TB of data daily without significant performance degradation.”

3. What strategies do you use for optimizing database performance?

Performance optimization is critical for data engineers, and this question evaluates your technical expertise.

How to Answer

Discuss specific techniques you’ve employed, such as indexing, query optimization, or database partitioning.

Example

“I focus on indexing frequently queried columns and regularly analyze query performance using tools like AWS CloudWatch. In one instance, I reduced query execution time by 50% by optimizing the indexing strategy and rewriting complex queries.”

4. Can you explain your experience with data modeling and representation?

Data modeling is essential for effective data management, and this question gauges your understanding of the concept.

How to Answer

Describe your approach to data modeling, including any tools or methodologies you use.

Example

“I utilize ER diagrams for conceptual modeling and prefer using tools like DBT for transforming data. I ensure that my models are flexible and can adapt to changing business requirements, which has helped my teams maintain agility in our data processes.”

5. Describe a challenging data engineering problem you faced and how you solved it.

This question allows you to showcase your problem-solving skills and technical knowledge.

How to Answer

Provide a specific example, detailing the problem, your approach, and the outcome.

Example

“In a previous project, we faced data latency issues due to a bottleneck in our ETL process. I analyzed the workflow and identified that a specific transformation step was taking too long. I restructured the process to run in parallel, which reduced our data refresh time from hours to minutes.”

Behavioral Questions

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

This question assesses your time management and organizational skills.

How to Answer

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

Example

“I prioritize tasks based on their impact and urgency. I use the Eisenhower Matrix to categorize tasks and ensure that I focus on high-impact activities first. This approach has helped me manage multiple projects effectively without compromising quality.”

2. Describe a time when you had to collaborate with cross-functional teams. How did you ensure effective communication?

Collaboration is key in a cross-functional environment, and this question evaluates your interpersonal skills.

How to Answer

Share a specific example of collaboration, highlighting your communication strategies.

Example

“I worked on a project that required input from both the data science and product teams. I scheduled regular check-ins and used collaborative tools like Slack and Trello to keep everyone updated. This ensured that we were aligned on goals and timelines, leading to a successful project launch.”

3. How do you handle feedback and criticism from peers or supervisors?

This question gauges your ability to accept and learn from feedback.

How to Answer

Discuss your mindset towards feedback and provide an example of how you’ve used it to improve.

Example

“I view feedback as an opportunity for growth. In a previous role, I received constructive criticism on my documentation practices. I took it to heart, sought additional training, and improved my documentation, which was later praised by my team for its clarity and usefulness.”

4. Can you give an example of a time you had to adapt to a significant change at work?

Adaptability is crucial in a fast-paced startup environment, and this question assesses your flexibility.

How to Answer

Share a specific instance where you successfully adapted to change.

Example

“When our team shifted to a remote work model, I quickly adapted by setting up a home office and establishing a structured daily routine. I also initiated virtual team-building activities to maintain morale and collaboration, which helped us stay connected during the transition.”

5. Why do you want to work at Extend?

This question assesses your motivation and cultural fit within the company.

How to Answer

Express your enthusiasm for the company’s mission and how your values align with theirs.

Example

“I am excited about Extend’s innovative approach to fintech and its commitment to enhancing the customer experience. I believe my background in data engineering aligns well with your goals, and I am eager to contribute to a company that values growth and collaboration.”