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Coupang interview notes, page 2 of 2

Large Enterprises

Screna has 15 Coupang interview write-ups. The most reported round is the system design round (6).

15 interview notes · updated Jul 2026

Coupang·Software Engineer·Technical Phone Screen

Jun 2026
Coupang coding round for a software engineer role, basically one parsing and sorting question that sounds easy until you actually sit down to think through the edge cases.
  • You're given a list of strings in the format 'product,price,attention'. Parse them into records, skip any malformed entries, and return the product names sorted by price ascending, then attention descending, then product name alphabetically as a tiebreaker. Price and attention are integers. Walk through your approach, data structures, complexity, and write working code.

“I went straight to splitting on commas and wrapping the int conversions in a try/except to handle malformed rows, which felt right.”

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Coupang·Software Engineer·Onsite - Behavioral / Leadership

Jul 2026
Behavioral round at Coupang for a software engineer role, basically one big teamwork question stretched across the whole conversation.
  • Walk me through a meaningful team experience: what the team was trying to do, what you personally contributed, how responsibilities got divided, any friction that came up, and what the result was. Be specific about your part versus everyone else's, and be ready to justify the calls you made.

“This felt like one question but it was really five.”

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Coupang·Software Engineer·Technical Phone Screen

Jul 2026
Coupang technical interview that basically boils down to one big project deep-dive. You pick something from your resume and they just pull on every thread until something unravels.
  • Pick a project from your resume and walk through the problem you were solving, your specific role, the technical decisions you made and why, any trade-offs, obstacles you ran into, and what the end result actually was.

“This sounds manageable until you realize they're not just listening politely.”

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Coupang·Software Engineer·Technical Phone Screen

Jul 2026
Coupang SWE interview with a grid-based algorithm problem that had a bunch of follow-ups stacked on top of each other. The core question was manageable but the follow-ups kept coming and I wasn't fully prepared for all of them.
  • Given an n x n binary grid with exactly two separate islands, what is the minimum number of water cells you need to flip to land in order to connect the two islands? Walk through your algorithm, argue why it's correct, and give the time and space complexity.
  • Implement a solution that first identifies one island completely, then expands outward from it to reach the second island.
  • What techniques can you use to avoid stack overflow when doing the initial island discovery, especially on large grids?
  • How does your solution scale for grids up to 2000 by 2000? What are the bottlenecks?
  • How would you modify your solution to avoid mutating the input grid at any point?

“BFS from one island expanding outward layer by layer felt like the right move, and I got there eventually, but my initial instinct was to just try all pairs of cells from each island and compute distances which is obviously way too slow.”

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Coupang·Software Engineer·Onsite - System Design / Architecture

Jul 2026
System design round at Coupang focused entirely on PKI infrastructure. Pretty deep dive, they wanted the full picture from root CA down to how clients actually validate a trust chain, not just a surface-level answer.
  • Design a full PKI system, including the certificate authority hierarchy, how certificates are issued and signed, revocation mechanisms, key storage, certificate lifecycle and rotation, client-side trust chain validation, and how you'd scale and keep CAs highly available.

“This is a lot to cover in one question and I think I front-loaded too much time on the CA hierarchy and didn't leave enough room for revocation.”

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