eBay Interview Questions — Page 5

eBay·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at eBay where the interviewer seemed to be figuring out what he wanted as we went. The question was fine but the whole thing felt a bit directionless, and it ended up veering into DevOps territory instead of the deep dive I was expecting.

Design a system to migrate data from a relational database to DynamoDB.
What key indicators would you monitor during and after a database migration?

“The question itself is reasonable but the interviewer kept shifting what he cared about.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

Interviewed for a software engineer role at eBay and got a classic graph traversal problem. Nothing too surprising but it's the kind of question where you either know the pattern or you're fumbling around for ten minutes.

Given a 2D grid of '1's (land) and '0's (water), count the number of distinct connected land regions, where connections are only horizontal or vertical.

“Classic islands problem.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

SQL-heavy technical screen for a Software Engineer role at eBay. The whole thing was basically one big window functions question broken into parts, which sounds manageable until you're actually writing ROWS BETWEEN framing live on a shared editor.

Given a table with user events (user_id, event_time, event_type, value), write SQL to compute each user's rolling 7-day sum of value by day using window functions.
Using the same events table, rank each user's events chronologically with deterministic tie-breaking.
For every event in the table, return the last non-null value seen so far per user. Explain your window framing.

“I knew the general shape: PARTITION BY user_id, ORDER BY day, then ROWS BETWEEN 6 PRECEDING AND CURRENT ROW.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

eBay software engineer screen that started with a resume walkthrough and then pivoted hard into infrastructure fundamentals. A lot of ground covered fast, felt more like a trivia sprint than a real technical conversation.

Can you walk us through your resume and relevant experience?
How does Redis work under the hood? Explain its architecture.
What is a storage engine and what does it do?
What storage engines does MySQL support, and what data structures do they use internally?
What are Docker and Kubernetes, and what problems do they solve?
What is the difference between Docker containers and traditional virtual machines?

“Standard opener, nothing surprising.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

eBay technical phone screen for a software engineer role, one algorithmic question that looked manageable at first but has enough moving parts to trip you up if you haven't thought carefully about how to track completeness in a single pass.

Given a binary tree, count the number of subtrees that are both complete binary trees and have an even sum. Your solution should run in O(n) time using a post-order traversal where each node returns enough state to verify completeness without re-traversing.

“The even-sum part is trivial, just propagate sums upward.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

eBay software engineer interview with a coding question that looked like a simple frequency count but had enough edge cases to trip you up if you weren't careful about what exactly you were counting.

Given a list of user browsing sessions (each a list of product IDs), a target product, and an integer k, return the k products most frequently co-viewed with the target product. Only sessions containing the target product count, the target itself is excluded from results, ties broken by smaller product ID first.

“My first instinct was to just throw everything into a frequency map and sort, which is basically right, but I initially forgot to filter out sessions that don't contain the target at all.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

eBay software engineer interview with a coding round focused on designing an in-memory file system from scratch. Pretty straightforward concept but the follow-up discussion on data structures made it more interesting than I expected.

Design an in-memory file system where each file has a name and size. Implement addFile, getFileSize, deleteFile, and listFiles operations. listFiles should return entries formatted as 'name(size)', sorted by size descending with ties broken alphabetically.

“The CRUD operations were easy enough with a hash map, O(1) for everything.”

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eBay·Product Manager·Onsite - Product Sense / Strategy

Jun 2026

eBay PM interview focused heavily on marketplace dynamics, backlog prioritization, and how you'd run experiments without blowing up seller or buyer trust. Pretty structured but they pushed hard on the judgment calls behind the framework scores.

How would you define the product objective and identify target users for a marketplace initiative at eBay?
Walk me through how you would prioritize a product backlog for a marketplace team, given inputs from funnel data, support tickets, and competing stakeholder requests.
What if the highest-scored backlog item is strategically unimportant to the business right now? How do you handle that?
How would you manage execution from idea to launch, coordinating across design, engineering, analytics, and stakeholders?
What instrumentation needs to be in place before you launch a new feature?
How would you design an A/B test for a marketplace feature when network effects between buyers and sellers might contaminate the control group?
If listing completion rates improve after a feature launch but listing quality drops, what do you do?
How would you communicate a difficult product tradeoff to executives when the data doesn't give you a clean answer?

“I went straight to first-time sellers because the funnel drop-off there felt obvious, but they pushed back asking about buyer trust implications.”

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eBay·Software Engineer·Technical Phone Screen

Jun 2026

eBay coding round, pretty standard algorithmic stuff. They gave me a top-K frequency problem and wanted me to walk through the heap-based approach and talk complexity. Nothing too wild but the follow-up on bucket sort tripped me up a bit.

Given an array and an integer k, return the k most frequent elements. Walk through your approach and analyze the time complexity.

“I went straight to the frequency map and then a min-heap of size k, which is the expected path.”

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eBay·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at eBay focused entirely on cache and database consistency. The question had a lot of moving parts and I don't think I covered all of them as well as I should have.

You have a cache like Redis sitting in front of a relational database, and multiple app servers can update the same key at the same time. How do you design the system to prevent and resolve conflicts and race conditions? Cover write ordering, atomicity, versioning or compare-and-set, distributed locks, TTL and invalidation versus write-through or write-back, idempotent updates, and recovery from partial failures. Also talk through the API design, data model, consistency guarantees, and trade-offs.

“This one sprawled in a way I wasn't ready for.”

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