OpenAI Interview Questions — Page 42

OpenAI·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at OpenAI for a software engineer role, focused entirely on a POS payment system. Pretty deep dive, they wanted real answers on batch processing, consistency, and failure handling, not just a high-level diagram.

Design a payment system for in-store card-swipe (POS) scenarios, covering both authorization holds and end-of-day batch capture processing.
How would you design the APIs for authorization, capture, void, and refund operations, and how do you handle idempotency across these?
How do you handle retries and partial failures when forwarding a batch of captures to the credit card provider at midnight?
How do you reconcile authorization holds against captures, and what happens when there's a mismatch?
Walk through your data model for transactions, holds, captures, and settlements, and what consistency guarantees does it provide?
How would you scale this system across many merchants, and what observability would you build in?
How does your system handle fraud detection and declined authorizations from the credit card provider?

“This was the whole interview, basically.”

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OpenAI·Product Manager·Onsite - Product Sense / Strategy

Jun 2026

Interviewed for a PM role at OpenAI and got a strategy question that was basically 'here's a real product surface, go figure it out.' The kind of question where you can tell they actually want to see how you think, not just whether you memorized a framework.

Using only publicly available documentation, develop a go-to-market and product strategy for OpenAI's fine-tuning capabilities.

“The 'publicly available docs' constraint is the whole puzzle.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Jun 2026

Infrastructure Engineer interview at OpenAI that was pretty much one big system design session. They gave me a meaty open-ended problem and just let it run, which I wasn't fully prepared for.

Design a simple in-memory SQL-like query engine that supports filtering records by fields like name, age range, and ID. Walk through your data model, how you represent predicates, query execution strategy, and how you'd extend it to support AND/OR logic, sorting, and projection.

“This one sprawled in ways I didn't expect.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at OpenAI for a software engineer role. One question, big scope. I left feeling like I'd barely scratched the surface of what they were probably looking for.

Design a text-to-video generation system similar to Sora.

“This one is massive and I underestimated the scope going in.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at OpenAI for an infrastructure engineer role. The whole session was basically one giant question about building a CI/CD platform at scale, and they wanted you to go pretty deep on almost every layer of the stack.

Design a multi-tenant CI/CD platform similar to GitHub Actions. Walk through the workflow model, job scheduling, runner architecture, log handling, artifact storage, secrets management, and scalability concerns.
How would you handle log streaming and storage for a large number of concurrent CI jobs?
What are the main scalability bottlenecks in a CI/CD system like this, and how would you address them?
How would you design artifact handling and caching in a multi-tenant CI/CD platform?
How would you approach secrets management for a CI/CD platform serving many different organizations?

“This was basically the entire interview compressed into one prompt.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at OpenAI for a software engineer role. The question was a full deep-dive into crossword puzzle solving, which sounds like a fun toy problem until you're 20 minutes in and they're asking about constraint propagation and worst-case complexity.

Design a system that solves a crossword puzzle. Given a 2D board, a list of slots with positions and directions, and a word dictionary, return a completed board or confirm no solution exists. Walk through brute-force backtracking up to optimized approaches, and analyze worst-case complexity.

“I started with the naive thing, try every word in every slot, and they let me run with it for a bit before nudging toward optimization.”

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OpenAI·Machine Learning Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at OpenAI for an MLE role. The whole thing was one big open-ended question about building an image mining pipeline from scratch, no labels, massive scale. Walked out unsure if I'd gone deep enough on the active learning piece.

Design an end-to-end ML system that automatically surfaces novel or interesting images from a massive unlabeled corpus of 100M to 1B images, with only a small daily human labeling budget.
How do you define and measure 'interestingness' or novelty in images when you have no ground-truth labels at all?
Your novelty score keeps surfacing screenshots and watermarked stock photos. Where exactly in the pipeline do you catch this, and how?
With only a few hundred to a few thousand human labels per day, how do you allocate that budget to maximally improve the system over time?
How do you make sure the final output set of candidate images is diverse rather than just a pile of images from the single rarest cluster?
How would you evaluate whether this mining system is actually working, both in terms of human judgment and downstream model value?
After several months the embedding distribution has shifted and clusters that used to look rare now look common. How does the system adapt without re-labeling everything from scratch?

“This is the main question and it sprawls in every direction.”

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OpenAI·Software Engineer·Technical Phone Screen

Jun 2026

Interviewed for a software engineering role at OpenAI and got a coding question I'd actually seen before, which sounds like a gift until you realize I still barely got through it. C++ was my downfall here, the string and byte handling just slowed everything down and I ran out of time before any follow-up questions even came up. Rejected.

Design and implement a persistent key-value store.

“I'd seen this problem before so I figured it'd be fine.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at OpenAI for a software engineer role, focused entirely on building a payment processing backend. The question had a lot of moving parts and the follow-ups got pretty deep into consistency guarantees and ledger design.

Design the backend for a payment processing system that charges users through external payment providers, handles retries safely, and keeps a full audit trail.
Walk through exactly what happens when the PSP charge call times out. How do you avoid both double-charging the user and losing the payment entirely?
How would you implement a partial refund against a captured payment using a double-entry ledger?
A webhook for the same payment event arrives twice, and a separate webhook arrives out of order. How does your handler deal with each case?
How would you extend this system to support a marketplace model where funds are held and then paid out to sellers?

“This is a big open-ended one.”

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OpenAI·Backend Engineer·Technical Phone Screen

Jun 2026

Backend coding round at OpenAI that was basically a deep dive into IP address manipulation. One problem, but it had enough layers to keep you busy for the whole session.

Given a CIDR block like '192.168.0.0/24', write code to iterate over every IP address in the range. Then flip it: given a starting IP and a count, return the minimal set of CIDR blocks that exactly covers that range. Walk through your bit manipulation logic and handle edge cases at block boundaries.

“The first part felt manageable, converting the CIDR prefix length to a mask and stepping through the 32-bit integer space.”

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