Type · System Design
How would you design a system to detect potentially fraudulent transactions in real-time for a large number of customers? Discuss the components, data flow, and challenges.
Enterprise · Software Engineer Interview Guide
Sign up to see ATSHeadquartered in NetherlandsInterview language: English
How to Pass the ING Software Engineer Interview in 2026
The ING DNA (TL;DR)
ING values a strong sense of ownership and a pragmatic, results-oriented approach to problem-solving. They look for candidates who can demonstrate a clear understanding of business impact and can articulate how their technical contributions drive value for the company and its customers.
The ING Interview Loop
Your onsite loop will typically consist of 5 rounds.
- 1
Round 1
Recruiter ScreenMotivation, role fit, logistics. - 2
Round 2
Coding ScreenLeetCode-medium algorithmic problems under time pressure. - 3
Round 3
System DesignDistributed systems, trade-offs at scale, architecture under constraints. - 4
Round 4
Onsite CodingLeetCode-hard, debugging, code clarity, edge cases. - 5
Round 5
Behavioral / LeadershipPast evidence of ownership, influence, resolving conflict.
The Danger Zone: Top Reasons Candidates Fail
Based on our database of ING interview outcomes, avoid these common traps:
- Not considering potential overflow issues with large amounts.
- Floating-point precision issues not being addressed.
- Inefficient sorting or filtering of transactions.
- Incorrectly calculating profit by selling before buying.
Test Yourself: Real ING Questions
Three real prompts pulled from our database.
Type · Behavioral
Tell me about a time you had to work with a stakeholder (e.g., product manager, business analyst) who had requirements that seemed technically infeasible or detrimental to the system's long-term health. How did you approach the situation, and what was the outcome?
Type · Debugging
Here is a code snippet that attempts to calculate compound interest. It's producing incorrect results for certain inputs. Find the bug(s) and explain how to fix them.
+ many more questions, signals, and worked examples
Sign up to unlock the full ING grading rubric
ING Interview Question Bank
A sample from our database, grouped by round. Sign up to see the full set.
9 of 14 questions shown
1
Recruiter Screen
1- 1
Type · Motivation
Why are you interested in joining ING as a Software Engineer, and what aspects of our work in financial technology particularly appeal to you?
2
Coding Screen
3- 2
Type · Algorithmic
Given a list of financial transactions, each with a timestamp, amount, and currency, write a function to calculate the total balance for a given currency over a specified time range. Assume timestamps are Unix epoch seconds. - 3
Type · Algorithmic
Implement a function that takes a list of stock prices for a single stock over several days and returns the maximum profit that could have been made by buying and selling the stock once. If no profit can be made, return 0. - + 1 more questions in this round (sign up to unlock)
3
System Design
4- 4
Type · System Design
Design a system to process and store real-time stock market data feeds from multiple exchanges. The system should be able to handle high throughput, provide low-latency access to recent data, and support historical data analysis. - 5
Type · System Design
Design an API rate limiter for a banking application's public API. Consider different strategies (e.g., token bucket, leaky bucket) and how to handle distributed systems. - + 2 more questions in this round (sign up to unlock)
4
Onsite Coding
3- 6
Type · Algorithmic
Given a binary tree where each node represents a financial account balance, write a function to find the maximum sum of balances along any path from the root to a leaf. Handle cases with negative balances. - 7
Type · Debugging
Here is a code snippet that attempts to calculate compound interest. It's producing incorrect results for certain inputs. Find the bug(s) and explain how to fix them. - + 1 more questions in this round (sign up to unlock)
5
Behavioral / Leadership
3- 8
Type · Behavioral
Tell me about a time you had to work with a stakeholder (e.g., product manager, business analyst) who had requirements that seemed technically infeasible or detrimental to the system's long-term health. How did you approach the situation, and what was the outcome? - 9
Type · Behavioral
Describe a challenging technical problem you encountered on a past project. What steps did you take to diagnose and resolve it? What did you learn from the experience? - + 1 more questions in this round (sign up to unlock)
Unlock all 14 ING questions, free
No credit card. Every question with its framework, the grading signals interviewers score against, and a worked answer for each.
Interview tracks at ING
How ING's DNA translates across functions. Pick your role.
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Practice ING interviews end-to-end
ING Mock Interview
Run a live mock interview with our AI interviewer using ING-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.
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STAR Stories for ING Behavioral Rounds
Build a Story Bank of your past wins, mapped to the leadership signals ING interviewers grade on. Reuse them across every behavioral round.
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ING Interview Prep Hub
The frameworks behind every ING round: CIRCLES for product sense, hypothesis-driven debugging for analytical, STAR for behavioral. Learn each one in 10 minutes.
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Interview Frameworks
CIRCLES, STAR, AARRR, RICE, MECE. The exact frameworks that make ING interviewers nod instead of frown. Step-by-step playbooks with the moves and the pitfalls.
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Sample answers
What a strong answer to these ING interview questions shows.
How would you design a system to detect potentially fraudulent transactions in real-time for a large number of customers? Discuss the components, data flow, and challenges.
A strong answer shows: Integration of multiple detection techniques (rules, ML).; Emphasis on real-time processing and low latency.; Consideration of scalability, model drift, and feedback loops..
Tell me about a time you had to work with a stakeholder (e.g., product manager, business analyst) who had requirements that seemed technically infeasible or detrimental to the system's long-term health. How did you approach the situation, and what was the outcome?
A strong answer shows: Effective communication skills.; Problem-solving and negotiation abilities.; Understanding of technical constraints and business needs.; Collaborative approach..
Frequently asked questions
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