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ASML

Large Enterprises

ASML is a Dutch multinational company that designs and manufactures photolithography machines used in the production of semiconductor chips. It is the world's leading supplier of lithography systems, most notably being the sole producer of extreme ultraviolet (EUV) lithography equipment critical for advanced chip manufacturing.

5 interview notes · updated Jul 2026

ASML·Software Engineer·Onsite - Behavioral / Leadership

Jul 2026
Behavioral round at ASML for a data engineer role, pretty much one meaty question about working through uncertainty. Felt like they wanted a real story, not a textbook answer.
  • Tell me about a time you had to make meaningful progress when things were unclear, whether that was vague requirements, shifting priorities, missing data, or technology you'd never used before. Walk through what the situation was, how you narrowed down the uncertainty, how you decided when you had enough information to act, how you kept stakeholders in the loop about the risks, and what the outcome was. Also, what did you learn about how you make decisions?

“This one is deceptively hard because it sounds like a standard behavioral question but they're actually probing for a few different things at once: your tolerance for ambiguity, how you communicate risk without spiraling into endless analysis, and whether you actually learned something or just survived.”

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ASML·Software Engineer·Onsite - Behavioral / Leadership

Jul 2026
Behavioral round at ASML for a data engineer role, basically one big cross-functional collaboration question dressed up with a lot of sub-parts. Felt like they really wanted to stress-test whether you've actually worked with non-technical stakeholders or just think you have.
  • Tell me about a difficult project where you had to work across multiple teams or roles. Walk through the situation, your specific role, how you got everyone aligned on goals, how you handled disagreements or competing priorities, what communication rhythm you set up, and what the measurable outcome was. Also, what would you do differently if you ran that project again?

“This question has a lot of moving parts and I didn't realize until I was halfway through my answer that I'd skipped the 'competing priorities' piece entirely.”

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ASML·Software Engineer·Onsite - Behavioral / Leadership

Jun 2026
Behavioral round at ASML for a Data Engineer role, focused pretty heavily on leadership and initiative. Just one main question but they really wanted to dig into the specifics.
  • Tell me about a time you took ownership of a problem that wasn't formally assigned to you, pushed a decision forward without having authority, or drove a meaningful change within your team.

“They wanted a real story, not a vague 'I stepped up once' kind of answer.”

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ASML·Software Engineer·Technical Phone Screen

May 2026
Technical screen for a Data Engineer role at ASML, focused almost entirely on Spark optimization. The interviewer clearly knew their stuff and pushed hard on specifics, not just buzzwords.
  • How do you detect and handle data skew in a Spark job?
  • Walk me through how you minimize shuffle operations in a Spark pipeline.
  • When would you choose a broadcast join over a sort-merge join, and how do you make that call in practice?
  • How do you decide what to cache or persist in a Spark job, and how do you pick the right storage level?
  • How do you tune executor count, memory, cores per executor, and the shuffle partitions setting for a Spark job?
  • What is Adaptive Query Execution in Spark and how does it change the way you think about query tuning?
  • How do you read large datasets efficiently in Spark, particularly with Parquet files?
  • Can you walk through a real Spark job you optimized and the specific metrics that improved as a result?
  • Why do you try to avoid wide transformations and UDFs, and what do you use instead?

“Started with salting, which felt safe, but they immediately asked me to compare it against broadcast joins for the same skew scenario.”

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ASML·Software Engineer·Technical Phone Screen

Apr 2026
Technical screen for a Data Engineer role at ASML that went deep into Infrastructure as Code. The whole conversation was basically one long IaC deep-dive, which I wasn't fully expecting at this level. Left feeling okay about some parts and genuinely uncertain about others.
  • What is Infrastructure as Code and why does it matter in practice?
  • What's the difference between declarative and imperative IaC tools, and when would you choose one over the other?
  • How does Terraform manage state, and what problems can come up with it in a team environment?
  • How do you structure reusable modules in Terraform and what patterns have you used?
  • How do you handle secrets in an IaC setup without putting them in the repo?
  • How do you integrate IaC into a CI/CD pipeline, specifically around the plan and apply stages?
  • What is infrastructure drift and how do you detect and fix it?
  • How do you test Infrastructure as Code? What tools or approaches have you used?
  • Walk me through a real IaC setup you built or contributed to significantly.

“Started with this as a warmup and I almost over-explained it.”

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