Upstart interview notes, page 9 of 10

Mid-sized

Most of these Upstart write-ups come from Software Engineers (51), then Data Scientists (42) and Machine Learning Engineers (2). The most reported rounds are the technical phone screen (73), the behavioral / leadership round (8), the online assessment (4) and the multi-round onsite (4).

97 interview notes · updated Jul 2026

Upstart·Data Scientist·Technical Phone Screen

Jul 2026

Upstart data scientist interview that pushed into live coding territory. They had me simulate a radioactive decay problem in real time, which was a step up from just deriving the analytical answer on paper.

Write runnable code that Monte-Carlo simulates the decay of 100 particles across many trials, then use the simulation results to estimate the survival probability and compare it to the theoretical value.

“Screen sharing while coding under pressure is a different beast from just talking through math.”

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Upstart·Software Engineer·Technical Phone Screen

Jul 2026

Interviewed for a software engineering role at Upstart and got a math-meets-indexing problem that looked straightforward but had a few edge cases I didn't think through fast enough.

Given three integers num1, num2, and sum, find the first digit index (starting from index 0 at the ones place) where the provided sum differs from the actual result of num1 + num2.

“Took me a second to realize the tricky part isn't the arithmetic, it's the digit extraction and handling the case where the two numbers have different lengths.”

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Upstart·Data Scientist·Technical Phone Screen

Jul 2026

Upstart data scientist interview that leaned pretty hard into probability theory. The core question was a physics-flavored stats problem and it required you to actually derive something, not just name-drop a distribution.

You have 100 independent particles, each with the same known half-life. Derive the probability that exactly k particles (or at least one) are still undecayed after some time t.

“The setup sounds like a physics problem but it's really just asking you to chain together the exponential survival function and binomial probability.”

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Upstart·Software Engineer·Online Assessment (OA)

Jul 2026

Upstart's OA for the software engineer role had five coding questions total, though I only really remember three of them well enough to talk about. Nothing too wild, mostly algorithmic stuff, but a couple questions were trickier to implement cleanly than they looked.

Given a mapping of company names to their daily stock prices, find the three companies with the highest average price. Break ties alphabetically.
Given a list of 2D points, return the lower-left corner, width, and height of the smallest axis-aligned bounding rectangle.
Validate a partially filled 9x9 number board: no digit should repeat in any row, column, or 3x3 subgrid. Empty cells are marked with a dot.

“Seemed simple and mostly was.”

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Upstart·Software Engineer·Technical Phone Screen

Jul 2026

Interviewed for a software engineering role at Upstart and got the classic two-sum problem. Pretty standard coding screen, nothing too wild, but the follow-up about doing it in linear time is where things get interesting.

Given an array of integers and a target value, return the indices of the two numbers that sum to the target. Then solve it in O(n) time.

“Started with the brute force nested loop thing because my brain just goes there first.”

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Upstart·Software Engineer·Technical Phone Screen

Jul 2026

Did a technical screen for a software engineer role at Upstart and got a BST problem. Pretty standard algorithmic stuff but the edge case conversation went longer than I expected.

Given the root of a binary search tree and an integer k, return the k-th smallest value in the tree. How do you handle edge cases like an empty tree or k being out of bounds?

“Went with in-order traversal pretty quickly since BST in-order gives you sorted order.”

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Upstart·Data Scientist·Technical Phone Screen

Jul 2026

Stats-heavy technical screen for a DS role at Upstart. Two problems, both probability/estimation flavored. Felt more like a grad school exam than a typical DS interview, which I was not fully prepared for.

You have n i.i.d. measurements from a single unbiased thermometer with known variance. Propose an estimator for the true temperature and derive its variance.
Now you have two sets of measurements from two independent thermometers, each unbiased but with different variances. Construct a linear unbiased combined estimator that minimizes variance. What are the optimal weights and the resulting variance?
For a 2D simple random walk where each step moves one unit in one of four directions with equal probability, compute the correlation between the x-coordinate and y-coordinate after n steps.
For the same 2D random walk, what is the correlation between the absolute values of the x and y coordinates after n steps? If a clean closed form is hard, give the sign and describe the asymptotic behavior.

“The sample mean is the obvious answer and I got there fine.”

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Upstart·Data Scientist·Technical Phone Screen

Jul 2026

First round technical screen for a Data Scientist role at Upstart. One probability puzzle, felt more like a math exam than a data science interview, but I guess that's just how it goes there.

A fair coin is tossed 1,000 times. A new streak begins on the first toss and every time the result differs from the previous toss. What is the expected number of streaks? Then generalize: what if the coin lands heads with probability p?

“I stared at this for longer than I'd like to admit.”

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Upstart·Data Scientist·Onsite - Cross-functional / Panel

Jul 2026

Went through a few conversational rounds at Upstart for a Data Scientist role, mostly behavioral stuff with the hiring manager and some cross-functional folks. Nothing too technical, but they pushed hard on collaboration and trade-off stories.

Tell me about a project where you worked closely with product, engineering, and design teams.
How did you handle conflicting priorities across teams?
Describe a time you had to make a difficult trade-off under a tight deadline. What happened?
How would your past teammates describe the way you work?
What motivates you outside of work?

“I had a decent story ready but fumbled the part about design.”

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Upstart·Software Engineer·Technical Phone Screen

Jul 2026

Upstart software engineer interview with a simulation-style coding problem that looks manageable until you actually try to implement it. The queue and revenue tracking logic trips you up if you're not careful about the 'pay once' constraint.

You're given a buffet with a fixed seating capacity, a list of customer prices, and an event stream where each customer ID alternates between arriving and leaving. Implement a function that returns total revenue, where a customer only pays the first time they're seated, never on return visits.

“The event encoding is what gets you first.”

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