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eBay interview notes, page 3 of 6

Large Enterprises

Most of these eBay write-ups come from Software Engineers (47), then Product Managers (4) and Backend Engineers (1). The most reported rounds are the technical phone screen (32), the system design round (9), the behavioral / leadership round (4) and the product sense round (4).

53 interview notes · updated Jul 2026

eBay·Software Engineer·Onsite - Behavioral / Leadership

May 2026
Behavioral round at eBay for a software engineer role. One question, classic influence-without-authority setup. Nothing too surprising but it made me realize how thin my actual story was when I tried to tell it out loud.
  • Tell me about a time you influenced a significant decision where you weren't the one with final authority. What was the decision, how did you build the case, and what happened?

“I had a story ready but it kind of fell apart when they pushed on the 'how did you get buy-in' part.”

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eBay·Software Engineer·Onsite - System Design / Architecture

May 2026
eBay system design round for a software engineer role. One big open-ended question about migrating an e-commerce service from a relational DB to DynamoDB, and they wanted the whole picture: schema analysis, data modeling, backfill, live traffic, validation, cutover, rollback, monitoring. A lot to cover in one session.
  • Design a production migration system that moves an existing e-commerce service from a relational database to DynamoDB with minimal downtime. Cover schema analysis, DynamoDB data modeling, historical backfill, capturing ongoing writes during migration, data validation, traffic cutover, rollback strategy, and monitoring.

“This thing is basically eight questions stapled together and they expect you to connect them into a coherent design, not just rattle off each part separately.”

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eBay·Software Engineer·Onsite - System Design / Architecture

May 2026
System design round at eBay for a software engineer role. The whole session was basically one giant question about building a marketplace backend, and they just kept pulling on threads until something unraveled.
  • Design the core APIs and data model for an online marketplace where users can list items and others can buy them.
  • How would you design search and filtering for marketplace listings at scale?
  • Walk through your approach to image handling for user-uploaded listing photos.
  • How would you design a payments and escrow system for the marketplace?
  • How do you manage inventory and item availability to prevent overselling?
  • What's your approach to fraud and abuse prevention in a marketplace?
  • How would you implement rate limiting across the marketplace APIs?
  • Describe your observability strategy for this system, covering metrics, logging, and alerting.
  • How would you scale this system using partitioning, indexing, caching, and a CDN?
  • Design a multi-region deployment plan with disaster recovery for this marketplace.

“I started with the listing entity and worked outward.”

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eBay·Software Engineer·Technical Phone Screen

May 2026
eBay SWE interview with a pretty involved OOP/system design coding question. The problem looked like a straightforward file system at first but kept expanding with users, capacity limits, compression, and copying. Took more mental bandwidth than I expected for a single session.
  • Design an in-memory file system class that supports adding, deleting, listing, and searching files, managing per-user storage capacity, copying files, and compressing/decompressing files.

“This one kept growing.”

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eBay·Software Engineer·Technical Phone Screen

May 2026
eBay coding round with a list partitioning problem that sounds straightforward until you actually try to implement it cleanly. The merging step at the end tripped me up more than I expected.
  • Given a list of numbers, split them into two sublists by comparing each new number against existing elements: if any existing number is greater than the new one, add it to that list; otherwise add it to whichever list is shorter. Then merge both lists at the end.

“I read the rules twice and still coded the wrong condition first.”

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eBay·Software Engineer·Hiring Manager Screen

May 2026
Manager round at eBay for a software engineer role. The interviewer had a heavy accent which made communication a bit rough, and the main technical topic was recommendation systems.
  • How would you design a recommendation system?

“The accent made it harder to follow up on clarifying questions, so I just picked a direction and ran with it.”

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eBay·Software Engineer·Technical Phone Screen

May 2026
eBay software engineer interview that focused on extending an in-memory file system with a search operation. The coding part was straightforward enough but the design discussion at the end is where things got interesting.
  • You have an in-memory file system with addFile, getFileSize, and deleteFile already implemented. Add a findFiles(prefix, suffix) method that returns all matching file names formatted as 'name(size)', sorted by size descending and then alphabetically for ties.
  • Is a linear scan good enough for this file system at scale, or would you consider building a trie or suffix index? Walk through the trade-offs.

“Spent the first few minutes just making sure I understood the output format correctly because 'name(size)' is easy to get wrong under pressure.”

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eBay·Software Engineer·Onsite - System Design / Architecture

May 2026
eBay system design round, one big question that kept branching into sub-problems. Started with a single-machine setup and they kept pushing until we were talking about distributed merging and failure recovery. Felt like I was barely keeping up by the end.
  • Design a distributed service that tracks and returns the top-K most frequent items over a high-throughput event stream. Walk through the full system: API design, ingestion pipeline, approximate counting with sketches, sharding and merging across nodes, time-window semantics, and how it scales.

“This was basically the whole interview.”

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eBay·Software Engineer·Onsite - System Design / Architecture

May 2026
eBay software engineer interview that was basically one long question dressed up as several. They wanted the full picture on a service you actually owned, not just a vague story about something you touched.
  • Walk me through a service you owned end-to-end: what was the business goal, what was your specific role, and how was it architected?
  • What was the hardest trade-off you made while building or running that service?
  • Tell me about a significant incident on that service: what happened, what did you do, and what was the outcome?
  • How did you measure the impact of that service?
  • Looking back, what would you do differently?

“I had a good example ready but fumbled the architecture part a bit.”

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eBay·Software Engineer·Technical Phone Screen

May 2026
eBay software engineer interview with a tricky array problem that looked straightforward until the 'one optional change' twist showed up. The prefix-sum angle was expected but the extension to handle a single mutation took me longer than I'd like to admit.
  • Given an integer array, find the maximum length of an even-length contiguous subarray that can be made 'balanced' (first half sum equals second half sum) by changing at most one element within it to any integer.

“I started with the basic prefix-sum setup for balanced subarrays, which felt fine.”

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