ING Hubs Spain Backend Engineer interview questions & guide 2026

The following questions are representative of the patterns observed in our interview processes. While specific technical tasks may evolve, these categories capture the core competencies we evaluate.

Java Core & Ecosystem

These questions test your mastery of the language and the frameworks that serve as the backbone of our infrastructure.

• How do you manage memory and performance in Java applications?
• Explain the lifecycle of a Spring Boot bean and its scope.

Preparation is about more than just reviewing syntax; it is about demonstrating how you think. We look for engineers who approach problems systematically and communicate their thought process clearly.

• Role-related knowledge: You must be comfortable with Java and Spring Boot fundamentals. We evaluate your ability to apply these tools to solve real-world problems rather than just reciting definitions.
• Problem-solving ability: We value candidates who ask clarifying questions before diving into code. We want to see how you structure your logic and handle edge cases during live coding or architectural discussions.
• Collaboration & Communication: Technical excellence is only half the battle. We look for individuals who can explain complex technical concepts to non-technical stakeholders and work effectively within a collaborative, cross-functional team.

The interview process at ING Hubs Spain is designed to be rigorous yet transparent. It typically begins with an initial screening by HR to gauge your background and alignment with our values. If successful, you will progress to technical assessments, which may include a coding exam followed by one or more technical interviews with team leads and senior engineers.

Our philosophy is to prioritize hands-on engineering skills and practical problem-solving. You should expect a mix of theoretical questions, live pair programming, and deep dives into your past projects. We aim to assess not just what you know, but how you apply that knowledge to deliver value in a real-world, high-scale banking environment.

This timeline provides a high-level view of the journey from application to final decision. Use this to pace your study schedule, ensuring you have enough time to brush up on both your technical fundamentals and your behavioral stories. Keep in mind that while we strive for efficiency, the duration of the process can vary depending on team availability and the specific project needs.

Technical Depth

We evaluate your ability to write production-ready code. This means focusing on performance, security, and readability.

• Collections & Data Structures: Understand the internal workings and trade-offs.
• OOP Principles: Go beyond the basics; understand how they apply to large-scale system design.
• Spring Boot & Ecosystem: Know how beans, dependency injection, and configuration work under the hood.

Be ready to go over:

• Memory management and garbage collection.
• Concurrency and multithreading in Java.
• RESTful API design and best practices.

Architectural Mindset

We look for engineers who can see the bigger picture beyond the individual ticket.

• Microservices: How do you handle service discovery, communication, and fault tolerance?
• Database Design: How do you optimize queries and ensure data integrity?
• Scalability: How do you design systems that can handle high volumes of concurrent requests?

Example questions or scenarios:

• "How would you design a system to handle [X] requests per second?"
• "Explain how you would implement a circuit breaker pattern."

As a Backend Engineer, you will be responsible for the full lifecycle of your services—from design and development to testing and deployment. You will collaborate closely with product owners to turn business requirements into robust technical solutions.

You will spend a significant portion of your time writing clean, tested code and participating in peer code reviews to maintain high quality standards. Beyond coding, you will be expected to participate in architectural discussions, troubleshoot production issues, and contribute to the continuous improvement of our CI/CD pipelines. You are an owner of the software you build.

We look for candidates who combine technical proficiency with a proactive, team-oriented mindset.

• Must-have skills:
  • Proficiency in Java and the Spring ecosystem.
  • Strong understanding of OOP and design patterns.
  • Experience with relational databases and SQL.
  • Familiarity with version control (Git) and CI/CD practices.
• Nice-to-have skills:
  • Experience with cloud platforms (e.g., Azure or AWS).
  • Knowledge of containerization (Docker, Kubernetes).
  • Familiarity with messaging systems like Kafka or RabbitMQ.

Q: How long does the entire process usually take? The timeline can vary, but typically it spans a few weeks. We recommend checking in with your recruiter if you haven't received an update after your interview rounds.

Q: Is the technical interview focused on theory or practice? It is a blend of both. Expect to discuss core concepts, but be prepared to apply them in a live coding or refactoring scenario.

Q: What is the best way to stand out? Successful candidates demonstrate a passion for clean code and a deep understanding of why they make specific architectural decisions. Showing a genuine interest in the banking domain and our specific challenges at ING Hubs Spain goes a long way.

• Explain your thought process: During live coding, talk out loud. We want to know how you arrive at a solution, even if you make a mistake along the way.
• Be ready for refactoring: You may be asked to improve existing code. Focus on readability, performance, and adherence to clean code principles.
• Prepare your own questions: Use the interview to learn about the team's culture and current technical challenges. It shows engagement and helps you decide if the role is a good fit for you.

Joining ING Hubs Spain as a Backend Engineer offers the unique opportunity to work on high-impact financial systems that affect millions. Success in this role requires a solid grasp of Java and Spring Boot, a commitment to clean engineering, and the ability to work collaboratively in a fast-paced environment.

Prepare by reviewing core concepts, practicing your coding skills, and reflecting on your past project experiences. You have the potential to make a significant impact here, and we encourage you to approach your interviews with confidence and curiosity. For further insights and resources, continue exploring the guidance available to help you navigate your journey to joining our team.

This data represents the typical compensation landscape for this role. Use these figures as a benchmark to ensure your expectations align with the current market and the specific responsibilities of the position.