OpenAI
Leading AI research laboratory developing state-of-the-art foundation models like GPT-4.
5 Rounds
~21 Days
Very Hard
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
Data Engineer
•
Coding
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medium
Write a Python function to parse a massive JSONL file containing web crawl data, filter out documents with a high proportion of non-alphanumeric characters (spam/code), and yield batches of clean text. Assume the file is significantly larger than available RAM.
#Python
#Generators
#Memory Management
#Text Processing
Data Engineer
•
Coding
•
hard
Implement a rate limiter for our API. Given a stream of requests, allow a maximum of N requests per minute per user. If a user exceeds this, drop the requests. Optimize for high concurrency and minimal latency.
#Rate Limiting
#Concurrency
#Data Structures
#Redis
Data Engineer
•
Coding
•
medium
Given a list of conversational turns (user prompt, assistant response) with timestamps and session IDs, write a function to reconstruct the conversation threads. Note that some turns might arrive out of order or have missing timestamps.
#Data Structures
#Sorting
#Edge Cases
Data Engineer
•
Coding
•
easy
Write a function to merge overlapping time intervals. We use this to calculate the total active compute time for GPU clusters given a log of job start and end times.
#Intervals
#Sorting
#Python
Data Engineer
•
Coding
•
medium
Write a Python generator to efficiently parse a 500GB JSONL file containing conversation logs without loading the whole file into memory.
#Python
#Memory Management
#Generators
#File I/O
Data Engineer
•
Coding
•
medium
Given a stream of API requests, implement a sliding window rate limiter.
#Data Structures
#Concurrency
#Queues
Data Engineer
•
Coding
•
medium
Implement a function to merge overlapping text intervals (e.g., highlighting spans in a document).
#Sorting
#Arrays
#Intervals
Data Engineer
•
Coding
•
hard
Write a distributed map-reduce job from scratch in Python using multiprocessing to count token frequencies across multiple files.
#Python
#Multiprocessing
#MapReduce
#Concurrency
Data Engineer
•
Coding
•
medium
Given a list of data pipeline tasks with dependencies, write a function to return a valid execution order.
#Graphs
#Topological Sort
#DAGs
Data Engineer
•
Coding
•
medium
Implement an LRU cache with a TTL (Time To Live) for caching database queries.
#Data Structures
#Hash Maps
#Linked Lists
#Caching
Data Engineer
•
Coding
•
medium
Write a script to sample exactly K random lines from a massive text file in a single pass.
#Probability
#Reservoir Sampling
#Big Data
Data Engineer
•
Coding
•
hard
Implement a MinHash and Locality-Sensitive Hashing (LSH) algorithm to find near-duplicate documents in a massive corpus of web text.
#Hashing
#Probability
#Text Processing
#Big Data
Data Engineer
•
Coding
•
medium
Given a list of text spans representing PII (Personally Identifiable Information) redactions with start and end indices, write a function to merge overlapping intervals efficiently.
#Arrays
#Sorting
#Intervals
Data Engineer
•
Coding
•
medium
Implement a sliding window rate limiter for the OpenAI API that can handle high concurrency.
#Data Structures
#Concurrency
#Queues
Data Engineer
•
Coding
•
hard
Find the top K most frequent tokens in a continuous, infinite stream of text data.
#Streaming Algorithms
#Heaps
#Count-Min Sketch
Difficulty Radar
Based on recent AI-sourced data.
Meet Your Interviewers
The "Standard" Interviewer
Senior EngineerFocuses on core competencies, system constraints, and clear communication.
SimulateUnwritten Rules
Think Out Loud
Always explain your thought process before writing code or drawing architecture.