Roku Interview Questions & Experiences

Roku·Data Scientist·Technical Phone Screen

Jul 2026

Roku data scientist interview with a business case question about diagnosing a profit drop at a coffee shop. Pretty classic case framing but they clearly wanted to see structured thinking, not just gut instinct.

You're managing a coffee shop that's been losing profit lately. Walk through how you'd systematically figure out why, including what data you'd pull, which metrics you'd calculate, and what hypotheses you'd actually test.

“I started with revenue and immediately went into ticket size and customer volume, which felt right, but I forgot to anchor the funnel properly before jumping to hypotheses.”

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Roku·Data Scientist·Take-home Assignment

Jun 2026

Roku data science take-home, three SQL problems back to back with a shared schema. The questions were genuinely hard and I spent way longer on them than I expected. Not a vibe check, they clearly wanted to see if you could actually write production-grade SQL.

Given a schema with orders, order items, and refunds, write SQL to compute a 7-day rolling gross profit by product category bucket (Speakers vs everything else) for each calendar day in a specified date range. Treat refunds as negative profit applied on the refund date, not the order date.
For non-test, non-cancelled orders, identify the top 2 products by week-over-week revenue growth comparing a specific 7-day window to the prior 7 days. Refunds count as negative revenue on the refund timestamp date.
For users whose first event date falls within a given 6-day window, calculate D1 retention rate by country. D1 means the user had any event exactly one calendar day after their first event date.

“The rolling window part was fine, lag/lead stuff I can do in my sleep.”

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Roku·Software Engineer·Technical Phone Screen

Jun 2026

Roku SWE interview with a streaming/filtering problem that looks easy but has some gotchas worth thinking through. Pretty standard technical screen setup, one question, asked to walk through the solution and talk about testing.

Given a stream of ads where each ad has a topic and a company, filter the stream so that you only keep ads whose topic and company haven't appeared in any previously accepted ad. Solve it in O(N) time and be ready to discuss test cases.

“Two sets, one for topics one for companies, check both before accepting and add to both after.”

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Roku·Software Engineer·Technical Phone Screen

Jun 2026

Roku SWE interview split into two chunks: one where you walk through a project you led, and one where they put multithreaded code in front of you and ask you to tear it apart. The concurrency section can get pretty gnarly depending on what snippet they pick.

Walk us through a technical project you led, covering the architecture, the key decisions you made, the trade-offs involved, and what your specific contributions were.
Here is a short multithreaded code snippet. Identify any correctness or performance problems, explain the underlying memory model reason, and propose a fix.

“This part felt fine until they started poking at the trade-offs.”

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Roku·Software Engineer·Onsite - System Design / Architecture

Jun 2026

Roku system design round for a software engineer position. The main problem was building a thread-safe LRU cache from scratch, which sounds manageable until they start pushing on concurrency trade-offs and you realize how much there is to actually say.

Design and implement a thread-safe LRU cache with get and put operations that both run in O(1) time and can be called concurrently from multiple threads.

“I went with a hashmap plus doubly linked list, slapped a global mutex around everything, and called it thread-safe.”

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Roku·Data Scientist·Technical Phone Screen

Jun 2026

Roku data science interview with a stats intuition probe. Pretty conversational, but they really wanted you to simplify without losing the point.

How would you explain the bias-variance trade-off to someone without a technical background?

“I went with an analogy about fitting a curve through data points and rambled a bit about underfitting before getting to the balance part.”

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Roku·Data Scientist·Onsite - Behavioral / Leadership

May 2026

Behavioral round at Roku for a data scientist role, pretty heavy on cross-functional storytelling and communication. One meaty question that required a lot of moving parts to answer well.

Walk me through a time you worked with a PM and an engineer to deliver a data product or analysis that actually changed a business decision. Cover the situation, what you were responsible for, how you influenced people without direct authority, any methodological disagreements you had to work through, and how you aligned on timelines. Include a conflict you de-escalated, a trade-off you made, and what you'd do differently. Then explain how you'd present the same findings differently to a skeptical exec versus a junior engineer.

“This question is a lot.”

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Roku·Software Engineer·Hiring Manager Screen

May 2026

Behavioral round for a software engineer role at Roku, driven entirely by leadership principles. Came in expecting maybe two or three questions but they had a story for every principle on the list, plus follow-ups that went deeper than I anticipated.

Tell me about a time you put the customer's needs ahead of what was technically convenient or easy for your team.
Describe a situation where you took ownership of something that was technically outside your responsibility.
Walk me through a time you simplified a complex process or system. What was the before and after?
Tell me about a decision you made with incomplete information. How did you know you were right?
Give me an example of a project where you delivered results under significant constraints.
Tell me about a time you acted quickly without waiting for full alignment. What happened?
Describe a time you dug deep into a problem and found a root cause that wasn't obvious at first.
Tell me about a time you disagreed with a decision but ultimately committed to it. How did you handle the disagreement?

“I had a decent story here but fumbled the follow-up when they asked what data I used to validate that customers actually cared.”

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Roku·Data Scientist·Technical Phone Screen

May 2026

Roku data scientist interview that went deep into business analytics for a coffee shop scenario. Three-part case covering profit decomposition, causal inference without an experiment, and rapid experimentation design. Dense and technical, felt more like a consulting case than a typical DS screen.

Build a driver tree and decompose an 18% profit drop across unit volume, pricing and discounting, product mix, COGS changes, waste, and labor productivity. Specify exact formulas and your effect-ordering method.
A competitor opened two blocks away mid-July. Without running an A/B test, how would you estimate the incremental revenue impact on your shop? Walk through your identification strategy, data requirements, assumptions, and at least two robustness checks.
Design two experiments you can run within two weeks to test hypotheses around menu engineering or promotional timing. Include margin guardrails and a stopping rule.

“This is the kind of question where you can sound smart for five minutes and still not actually answer it.”

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Roku·Software Engineer·Onsite - System Design / Architecture

May 2026

System design round at Roku for a software engineer role, focused entirely on ad infrastructure. One meaty question about frequency capping that went pretty deep into distributed systems territory.

Design the frequency capping component of an ad-serving system. How do you prevent the same ad from being shown to the same user too many times within a rolling time window?

“This one sprawled fast.”

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