OpenAI

Leading AI research laboratory developing state-of-the-art foundation models like GPT-4.

5 Rounds ~21 Days Very Hard

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The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

All Roles Backend Engineer 1 Cloud Engineer 1 Data Engineer 4 Machine Learning Engineer 2

All Topics System Design 115 Algorithms 99 Culture Fit 61 Leadership 22 SQL 17 Machine Learning 12 Machine Learning Infrastructure 11 Distributed Systems 8

Backend Engineer • Technical • hard

Explain the Raft consensus algorithm. How does it handle network partitions?

#Consensus #Raft #Fault Tolerance

Practice

Cloud Engineer • Technical • hard

Explain the Raft consensus algorithm and how etcd uses it. What are the bottlenecks when scaling etcd to thousands of Kubernetes nodes?

#etcd #Raft #Kubernetes Internals

Practice

Data Engineer • Technical • medium

Compare and contrast Apache Spark and Ray. When would you choose Ray over Spark for data processing at OpenAI?

#Apache Spark #Ray #Architecture #Machine Learning

Practice

Data Engineer • Technical • medium

Explain how Broadcast Joins work in Spark and when they should be avoided.

#Apache Spark #Joins #Optimization

Practice

Data Engineer • Technical • hard

How do you ensure exactly-once processing semantics in a Kafka to Spark Streaming pipeline?

#Kafka #Spark Streaming #Exactly-Once #Checkpoints

Practice

Data Engineer • Technical • hard

Explain how you would handle an OutOfMemory (OOM) error in a Spark job processing a highly skewed dataset.

#Apache Spark #OOM #Data Skew #Performance Tuning

Practice

Machine Learning Engineer • Coding • hard

Implement a Ring All-Reduce algorithm simulation. Given an array of N nodes, each with an array of numbers, write code to perform the scatter-reduce and all-gather phases.

#Networking #Parallel Computing #Algorithms

Practice

Machine Learning Engineer • Technical • medium

What are the specific trade-offs between Tensor Parallelism (TP), Pipeline Parallelism (PP), and Fully Sharded Data Parallelism (FSDP)? When would you use each?

#Model Parallelism #GPU #Networking

Practice

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The "Standard" Interviewer

Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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Unwritten Rules

Think Out Loud

Always explain your thought process before writing code or drawing architecture.

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