Roblox interview notes, page 5 of 15

Large Enterprises

Most of these Roblox write-ups come from Software Engineers (79), then Data Scientists (38) and Machine Learning Engineers (17). The most reported rounds are the technical phone screen (85), the system design round (39), the online assessment (6) and the behavioral / leadership round (3).

142 interview notes · updated Sep 2026

Roblox·Data Scientist·Technical Phone Screen

May 2026

Roblox data science interview with a deep experimentation design question around social graph interference. One question, very technical, clearly aimed at senior-level candidates who've actually run clustered experiments before.

You're launching a feature that boosts feed content when friends interact with it. Because interactions spread through the social graph, standard user-level A/B randomization breaks down. How would you design an experiment that actually gives you a credible causal estimate? Walk through your randomization strategy, metrics, power calculations, analysis approach, and what you'd do if contamination gets out of hand mid-test.

“This is a five-part question dressed up as one question, which I did not fully appreciate until I was three minutes into talking about Louvain clustering and realized I hadn't even touched metrics yet.”

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Roblox·Software Engineer·Technical Phone Screen

May 2026

Roblox software engineer interview with a classic interval merging problem. Nothing too wild, but it's the kind of question that separates people who've actually coded recently from people who just think they have.

Given an array of intervals, merge all overlapping ones and return the resulting non-overlapping intervals.

“Sort by start time first, that's the key move.”

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Roblox·Data Scientist·Technical Phone Screen

May 2026

Roblox data scientist interview with a pretty meaty SQL question that required thinking through deduplication from two different angles at once. The schema was straightforward but the edge cases were the whole point.

Using two tables, app_sessions and payments, write a single SQL query returning daily and country-level metrics (DAU, payers, revenue, ARPDAU, ARPPU) for the last 7 days. Join payments to sessions on both user_id and session_id. Handle duplicate session rows in app_sessions, multiple payment rows per session, and unmatched payments that have no corresponding session.

“This one took me longer than I wanted to admit just to map out the dedup problem before writing a single line.”

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Roblox·Software Engineer·Technical Phone Screen

May 2026

Did a technical phone screen for a Software Engineer role at Roblox. One coding question, grid traversal, pretty standard stuff but they pushed on implementation details more than I expected.

Given a 2D grid with walkable cells and obstacles, a start cell and an end cell, determine if a character can reach the end using 4-directional movement. Walk through your implementation and explain how you handle visited tracking.

“I went with DFS because it felt faster to code under pressure.”

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Roblox·Data Scientist·Technical Phone Screen

May 2026

Roblox DS interview with a meaty causal inference question about a non-randomized feature rollout. One long multi-part problem that basically covers everything: confounding, DiD assumptions, regression specs, and failure modes. No fluff, just depth.

You work on a game platform and a new feature rolls out in a non-randomized way. More engaged users get it earlier, and there's seasonality in the data. How do you estimate the feature's causal effect on daily time spent, and how do you handle confounding?
If you use Difference-in-Differences for this problem, how do you define the treatment and control groups, what are the pre and post windows, and what regression would you actually run? Which coefficient gives you the answer?
What is the key identifying assumption behind DiD here, and how would you actually test or validate it?
What are the main ways DiD could fail in this setting, and what alternative methods would you use if DiD isn't credible?

“This is the kind of question where you can't just say 'run a t-test' and move on.”

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Roblox·Software Engineer·Onsite - System Design / Architecture

May 2026

Roblox system design round, one big question that expanded into about six different sub-problems before I could even finish my first diagram. The scope was brutal and I'm not sure I covered everything they wanted.

Design a payment authorization and delayed capture system, where funds are held at one time and either captured or released later. Cover the full flow with payment providers, how you'd schedule and expire jobs durably, partial captures, refunds, retry logic with dead-lettering, and exactly-once semantics for eventual capture.

“This question kept growing.”

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Roblox·Data Scientist·Technical Phone Screen

May 2026

Technical screen for a DS role at Roblox covering two coding problems, both stats-flavored. Nothing too wild but you need to actually remember your z-test formula and not just hand-wave through it.

Write a function that takes a historical array of observations, a significance level, a desired power, and a minimum detectable effect, then returns the required per-group sample size for a two-sided two-sample z-test.
Implement a function that computes P(A|B) given P(A), P(B|A), and P(B|not A) using Bayes' rule.

“I knew the formula conceptually but blanked on which z-values to pull for alpha and power.”

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Roblox·Machine Learning Engineer·Technical Phone Screen

May 2026

Phone screen for an MLE role at Roblox. Pretty low-key, the interviewer was relaxed and the question was straightforward enough that I didn't feel like I was being grilled.

Given a list of windows and a target number, determine which windows contain that target number.

“Simple sliding window type problem.”

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Roblox·Data Scientist·Technical Phone Screen

May 2026

Roblox DS interview had one big open-ended question that basically asked you to defend an entire ML project from soup to nuts. It felt less like an interview and more like a technical design review where you could easily get lost in the weeds.

Walk me through a production ML project end-to-end: how you framed the problem, defined the target, avoided label leakage, chose your data and metrics, engineered features, handled privacy or fairness constraints, picked and tuned a model, monitored it post-launch, measured business impact without a clean A/B test, and what you'd do differently on a second version.

“This question is a marathon.”

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Roblox·Data Scientist·Technical Phone Screen

May 2026

Roblox data scientist interview had a graph traversal coding question that was more algorithmic than I expected for a DS role. One question, but it had enough edge cases to keep me busy for a while.

Given a directed social graph as a list of follower/followee pairs and a starting user, write a recursive function that returns the maximum number of 'follow layers' reachable from that user. Must handle cycles without infinite recursion.

“The cycle handling is what tripped me up first.”

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