OpenAI Interview Questions — Page 15

OpenAI·Frontend Engineer·Technical Phone Screen

Apr 2026

Frontend Engineer interview at OpenAI that was basically one big refactoring exercise. The problem was a gnarly chat message processor full of mixed concerns and they wanted you to clean it up live while keeping a test passing.

You're given a messy JavaScript function that handles chat commands like /meet, /taco, and /away. It mixes parsing logic, command handling, and string manipulation all in one place. Refactor it for readability, modularity, and testability while keeping the existing test case green.

“This is the kind of question where you can talk yourself into a corner fast.”

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OpenAI·Software Engineer·Technical Phone Screen

Apr 2026

Got a pretty gnarly algorithmic problem at what seemed like a technical phone screen for a software engineer role at OpenAI. One question, lots of moving parts, and I left unsure if I'd even fully understood the problem statement by the time the call ended.

You have an N×M grid where some cells start infected. Infection spreads to 4-directional neighbors one step per day, and an infected plant dies if it ever had K or more infected neighbors simultaneously within D days of getting infected. You can burn (permanently remove) exactly one row or one column at the start of any single day. Find the optimal day and row/column to burn in order to minimize total plant deaths.

“I spent the first few minutes just trying to re-read the problem back to the interviewer because I kept confusing the death condition with the spread condition.”

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OpenAI·Software Engineer·Technical Phone Screen

Apr 2026

OpenAI software engineer interview that was basically a grid simulation problem broken into three escalating parts. BFS-heavy, and the follow-up variant was where things got interesting.

Given a 2D grid where each cell is either healthy, infected, or immune, simulate how infection spreads to 4-directional neighbors. First, implement basic spread until no more cells can be infected. Then compute the minimum time to fully infect the grid, returning -1 if it's impossible due to immune cells or disconnected regions. Finally, handle a follow-up variant with added constraints like multiple infection sources, immune blockers, or per-cell infection delays.

“The first part was fine, standard BFS from all infected cells simultaneously.”

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OpenAI·Machine Learning Engineer·Technical Phone Screen

Apr 2026

OpenAI ML engineer round where you get handed a 400+ line PyTorch codebase and have to complete three required sections plus a bonus. The complexity questions sprinkled throughout caught me more off guard than the coding itself.

Given a large PyTorch codebase, complete the required implementation sections and reason about the time and space complexity of the operations you write.
What is the time and space complexity of matrix multiplication A @ B for two tensors A and B?

“The coding part was manageable but I kept second-guessing my tensor shapes mid-implementation.”

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OpenAI·Software Engineer·Technical Phone Screen

Apr 2026

Interviewed for a software engineering role at OpenAI and got a coding question about GPU credits. Short and focused, not much else to report.

Design or implement a system for tracking and managing GPU credit usage.

“This felt pretty domain-specific to OpenAI which made sense in retrospect but I wasn't expecting it.”

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OpenAI·Software Engineer·Technical Phone Screen

Apr 2026

Interviewed for an iOS role at OpenAI and got a coding problem that was basically a mini billing system for GPU credits. Not what I expected going in, but it made sense given what they're building.

Design and implement a credit ledger system that supports crediting an account, debiting credits for usage events, querying the current balance, and optionally reverting a past transaction. Discuss the data structures you'd use and analyze the time and space complexity.

“Took me a minute to realize this wasn't just a simple balance tracker.”

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OpenAI·Software Engineer·Technical Phone Screen

Apr 2026

Data science interview at OpenAI, one of those analytical rounds where they throw a messy scenario at you and want to see how you think under pressure.

You're looking at an experiment where different metrics moved in opposite directions. How do you make sense of that and decide what to do next?

“This tripped me up more than I expected.”

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OpenAI·Product Manager·Onsite - Product Sense / Strategy

Apr 2026

PM interview at OpenAI, one question about how you'd handle shipping a powerful but potentially dangerous new capability. Short and sharp, but it made me sweat more than I expected.

You have a new capability that's extremely powerful but could also cause serious harm. How do you decide whether to ship it?

“I went straight to a risk-benefit framework and immediately regretted how textbooky it sounded.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Apr 2026

System design round at OpenAI for a software engineer role, full hour on designing a Slack-like messaging platform. It was one of the more thorough design questions I've had, they wanted depth on basically every layer of the stack.

Design a real-time messaging platform similar to Slack, covering workspaces, channels, direct messages, threaded replies, reactions, presence, notifications, search, file attachments, and message edit/delete with audit history.
How would you design the message ingestion and fan-out path, and what are the tradeoffs between push and pull delivery to channel subscribers?
How would you handle real-time delivery using persistent connections, and how does the gateway tier interact with your message broker?
Walk me through how you'd design a presence service to track which users are online.
How would you implement full-text search across messages while enforcing access control so users only see results from channels they're members of?
How would you handle storage tiering for message history, separating recent messages from older archived data?
How would you partition and scale the system across millions of workspaces?
How would you track unread message counts and read receipts efficiently?

“This is a beast of a question and I underestimated how much ground they actually wanted to cover.”

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OpenAI·Software Engineer·Onsite - System Design / Architecture

Apr 2026

System design round for an infrastructure role at OpenAI, centered entirely on building a YouTube-scale video storage and delivery platform. It was a long session and the scope kept expanding every time I thought I'd covered enough ground.

Design a video publishing and storage system at YouTube scale, covering the full pipeline from upload to playback.
How would you structure object storage for video assets, including all codec and resolution variants plus manifest files?
Walk through the transcoding pipeline: how do you handle per-codec and per-resolution variants, and how do HLS/DASH manifests fit in?
How would you design the thumbnail generation service and integrate it with the rest of the pipeline?
How do you design the metadata service for a video platform at this scale, and what does the data model look like?
How would you handle CDN distribution and viewer playback flow, especially for high-traffic content?
What caching strategy would you use for hot content, and how do you manage lifecycle and storage costs for cold or rarely accessed videos?

“The question started deceptively simple and then they just kept pulling the thread.”

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