Software Engineer
Posted Sep 11, 2026 · We last checked this listing on Oct 6, 2026
Likely interview questions for this role
Written from this job description, not a generic list. Each one notes what the interviewer is really checking.
About your past
Tell me about the most performance-sensitive code you have written. How did you measure and improve it?
What they are checking: Whether they optimize based on measurement rather than guesses, which matters in high speed trading.
Tell me about a time you worked closely with non-engineers, like traders, to build something they needed.
What they are checking: Ability to translate trading needs into software and work side by side with users.
Describe a bug that took you a long time to find. What finally cracked it?
What they are checking: Persistence and a systematic approach to hard problems.
What would you do
Your main experience is in Java or C#. How would you get productive in our C++ codebase on Linux?
What they are checking: Honest self-assessment and a real plan for learning, since the posting accepts other languages.
A trading strategy is behaving oddly in production during market hours. How do you debug without making it worse?
What they are checking: Judgment under pressure, including when to stop trading and how to investigate safely.
About the work
In C++, how would you avoid memory allocation on a hot path?
What they are checking: Knowledge of object pools, preallocation and why allocation causes latency spikes.
What happens in a CPU cache when your data structures are laid out badly? How would you fix it?
What they are checking: Understanding of cache locality, which separates fast trading code from merely correct code.
How would you design an execution engine component that receives market data and sends orders with low latency?
What they are checking: Ability to reason about the full data path and where time is spent in a trading system.
What makes C++ code reusable and reliable over years, not just fast today?
What they are checking: Whether they balance speed with clean design, testing and maintainability.
What Linux tools do you use to see what a process is doing?
What they are checking: Practical Linux debugging skill with tools like perf, strace or top.
How would you analyze a large amount of market data quickly to answer a trader's question?
What they are checking: Whether they can choose the right tools and approach for high speed data analysis.
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Practice this out loudThe full job description
As published by Simplex Trading.