Ing Deutschland Backend Engineer interview questions & guide 2026

The following questions reflect patterns observed in previous candidate experiences. While specific technical requirements may shift based on the team’s current project, these categories capture the essential competencies evaluated at Ing Deutschland.

Technical Proficiency and Coding

These questions assess your ability to write clean, maintainable code and your proficiency in core backend technologies.

• Can you walk us through the implementation of a specific REST API you designed?
• How do you ensure your code adheres to best practices and industry standards?

Preparation should focus on demonstrating both technical depth and a professional, communicative approach. You are expected to show that you can handle technical challenges while remaining aligned with the operational realities of a large, regulated organization.

Technical Competence – Your ability to write robust, production-ready code is the baseline. You should be prepared to discuss your design decisions, the trade-offs you made, and how your solutions scale under load.

Security-Minded Engineering – At Ing Deutschland, security is not an afterthought. You will be evaluated on your proactive approach to identifying vulnerabilities and your knowledge of secure coding patterns.

Communication and Professionalism – The ability to clearly explain your thought process is as important as the code itself. You should be ready to articulate your technical choices and respond to feedback or follow-up questions with clarity and composure.

The interview process at Ing Deutschland is designed to evaluate both your technical capability and your fit for a regulated, high-stakes environment. Candidates should expect a structured, albeit sometimes deliberate, pace. Typically, you will begin with an initial screening followed by a technical assessment, which serves as a core gate in the evaluation process.

This timeline provides a visual overview of the standard progression from initial engagement to final evaluation. You should use this to pace your study, ensuring you are prepared for the transition from high-level technical discussions to deep-dive security or architectural reviews.

Technical Assessment

The coding challenge is a critical component of your application. It is used to gauge your technical standard and your ability to follow specifications.

Be ready to go over:

• Implementation of RESTful services.
• Data structures and algorithmic efficiency.
• Code modularity and adherence to clean code principles.

Example questions or scenarios:

• "Write a service that performs complex financial calculations based on provided input parameters."
• "Refactor an existing piece of code to improve performance and readability."

Security and Compliance

Security is a recurring theme in final-stage interviews. Demonstrate that you understand the "why" behind security protocols, not just the "how."

Be ready to go over:

• Input validation and sanitation.
• Secure API design principles (e.g., OAuth, JWT).
• Protecting against common vulnerabilities (e.g., OWASP Top 10).

Example questions or scenarios:

• "How do you protect against SQL injection in your database queries?"
• "Describe a scenario where you had to balance feature delivery with a security requirement."

As a Backend Engineer, you will spend your time designing, developing, and maintaining the services that keep Ing Deutschland running. You will collaborate closely with product owners and frontend engineers to define API contracts and integrate backend services with the broader ecosystem.

Your day-to-day will involve writing high-quality code, participating in peer code reviews, and contributing to architectural discussions. You will be expected to take ownership of features from conception to deployment, ensuring that your deliverables are not only functional but also secure and maintainable.

A successful candidate for the Backend Engineer position typically possesses a strong foundation in Java or equivalent backend technologies. You should be comfortable working in an environment that prioritizes stability and security.

• Must-have skills: Proficient in Java or a major JVM language, deep understanding of REST API development, and familiarity with relational databases.
• Nice-to-have skills: Experience with cloud-native architectures (e.g., AWS, Azure), containerization (Docker, Kubernetes), and familiarity with microservices patterns.
• Experience level: A proven track record of delivering production-level backend services, ideally within a team-based, agile environment.

Q: How long should I expect the entire process to take? A: The duration can vary significantly. While some candidates move through quickly, others may experience delays between stages. It is advisable to remain patient while maintaining a professional follow-up schedule.

Q: What is the most important thing to focus on for the technical interview? A: Focus on clean, readable code and clear communication. Interviewers want to see that you can solve the problem effectively and explain your reasoning behind specific design choices.

Q: How much should I prepare for the security-focused interview? A: Do not underestimate this stage. Review fundamental security concepts relevant to web applications and be prepared to discuss them in the context of a banking environment.

• Own your follow-ups: If you do not hear back within the expected timeframe, send a polite, professional follow-up email. Persistence is appropriate, but keep it concise.
• Clarify the task: If you receive a coding challenge with ambiguous requirements, do not hesitate to ask for clarification before starting.
• Document your work: When submitting a coding task, include a README file that explains your approach, the trade-offs you made, and how to run your code.

Securing a Backend Engineer role at Ing Deutschland requires a balance of technical precision and a disciplined approach to security. By preparing for the coding challenge with a focus on best practices and ensuring you are well-versed in security fundamentals, you will position yourself as a strong candidate.

Remember that the interview process is a two-way street. While you are being evaluated, use the opportunity to gauge whether the team’s culture and the nature of the work align with your career goals. With focused preparation and a professional approach, you can navigate the process effectively and demonstrate your value to the team.