OpenAI

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

5 Rounds ~21 Days Very Hard

Start Mock Interview

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 35 Cloud Engineer 50 Data Engineer 85 Data Scientist 50 DevOps Engineer 35 Frontend Engineer 35 Full Stack Engineer 35 Machine Learning Engineer 50 Product Manager 50 Software Engineer 119

All Topics Algorithms 8 System Design 7 JavaScript Fundamentals 5 Culture Fit 4 React 3 UI Components 3 Web Fundamentals 1 Performance 1

Frontend Engineer • Behavioral • medium

Tell me about a time you had to build a complex UI feature with highly ambiguous requirements. How did you determine what to build?

#Ambiguity #Product Sense #Communication

Practice

Frontend Engineer • Behavioral • easy

Why do you want to work at OpenAI? How do you align with our mission to ensure that artificial general intelligence benefits all of humanity?

#Mission Alignment #Motivation #AI Safety

Practice

Frontend Engineer • Behavioral • medium

Describe a situation where you had to make a difficult trade-off between shipping quickly and writing perfect, scalable code. What was the outcome?

#Trade-offs #Delivery #Technical Debt

Practice

Frontend Engineer • Behavioral • medium

Tell me about a time you disagreed with a product manager or designer about a user experience decision. How did you resolve it?

#Conflict Resolution #Collaboration #User Empathy

Practice

Frontend Engineer • Behavioral • medium

Give an example of a complex technical problem you solved that required you to learn a completely new technology or framework on the fly.

#Adaptability #Learning #Problem Solving

Practice

Frontend Engineer • Coding • medium

Implement a custom React hook `useStreamingResponse(url, prompt)` that connects to an SSE endpoint, accumulates the streamed text chunks, and returns the current text and a boolean indicating if the stream is complete.

#React Hooks #Server-Sent Events #Asynchronous JavaScript

Practice

Frontend Engineer • Coding • hard

Write a function to parse and render a continuous stream of Markdown text. How do you handle incomplete Markdown tokens (e.g., a code block that has started with '```' but hasn't closed yet)?

#Parsing #String Manipulation #Edge Cases

Practice

Frontend Engineer • Coding • hard

Implement a virtualized list component from scratch in React to render a chat history with 100,000 messages of variable heights.

#Performance #DOM Manipulation #React

Practice

Frontend Engineer • Coding • medium

Write a debounce function that includes an `immediate` flag, allowing the function to trigger immediately on the first call and then debounce subsequent calls.

#Closures #Timers #Higher-Order Functions

Practice

Frontend Engineer • Coding • medium

Implement a custom `Promise.allSettled` function from scratch.

#Promises #Asynchronous JavaScript #Error Handling

Practice

Frontend Engineer • Coding • medium

Implement a rate-limit UI component. When a user hits a rate limit (e.g., GPT-4 usage cap), the submit button should disable and show a live countdown timer until they can prompt again.

#React #Time Management #State Management

Practice

Frontend Engineer • Coding • medium

Write a function to deeply merge two JavaScript objects. It should handle nested objects, arrays, and edge cases like null or undefined.

#Recursion #Data Structures #Type Checking

Practice

Frontend Engineer • Coding • medium

Implement an LRU (Least Recently Used) Cache class in JavaScript. It should have `get(key)` and `put(key, value)` methods, both operating in O(1) time complexity.

#Data Structures #Hash Maps #Linked Lists

Practice

Frontend Engineer • Coding • medium

Write a function that takes a string of HTML and returns true if the tags are properly balanced and nested, and false otherwise.

#Stacks #String Parsing #Regex

Practice

Frontend Engineer • Coding • hard

Implement a rich text editor component that supports @mentions. When a user types '@', a dropdown should appear to select different AI models (e.g., GPT-3.5, GPT-4).

#DOM Manipulation #Event Handling #Positioning

Practice

Frontend Engineer • Coding • easy

Write a function to traverse the DOM tree starting from a given node and return an array of all text nodes that match a specific regular expression.

#DOM API #Tree Traversal #Recursion

Practice

Frontend Engineer • Coding • medium

Implement an Event Emitter class with `on`, `off`, `once`, and `emit` methods.

#Design Patterns #Data Structures #Context

Practice

Frontend Engineer • Coding • medium

Write a custom React hook `useFetch` that takes a URL and options. It should handle loading state, error state, caching responses, and aborting the request if the component unmounts.

#React Hooks #Network #AbortController

Practice

Frontend Engineer • Coding • hard

Implement a function that schedules tasks with a maximum concurrency limit. It should take an array of functions (returning promises) and a concurrency number.

#Promises #Concurrency #Queues

Practice

Frontend Engineer • Coding • medium

Write a function to find the shortest path between two DOM elements in the DOM tree (i.e., finding their lowest common ancestor and the path to it).

#DOM API #Tree Traversal #Pointers

Practice

Frontend Engineer • Coding • hard

Implement a basic reactive state system (similar to Vue or MobX) using JavaScript Proxies. When a property on the state object is accessed, register the current observer. When it is mutated, trigger the observers.

#Proxies #Design Patterns #Reactivity

Practice

Frontend Engineer • Coding • hard

Write a function to serialize a DOM tree into a JSON object, and another function to deserialize that JSON object back into a DOM tree.

#DOM API #Serialization #Recursion

Practice

Frontend Engineer • System Design • hard

Design the frontend architecture for the ChatGPT web client. Focus specifically on how you would handle streaming responses, manage conversation state, and handle network interruptions.

#Architecture #Streaming #State Management #Resilience

Practice

Frontend Engineer • System Design • hard

Design a real-time collaborative prompt engineering playground where multiple users can edit a prompt simultaneously and see live model outputs.

#WebSockets #Operational Transformation (OT) #CRDTs #Concurrency

Practice

Frontend Engineer • System Design • medium

Design an image gallery for DALL-E generations. It needs to support infinite scrolling, lazy loading of high-res images, and a masonry layout.

#Layout #Performance #Intersection Observer

Practice

Frontend Engineer • System Design • hard

Design a robust file upload system for the Advanced Data Analysis (Code Interpreter) feature. It must handle files up to 1GB, support resume on failure, and show progress.

#Chunked Uploads #Network Resilience #File API

Practice

Frontend Engineer • System Design • hard

Design a canvas-based node editor (similar to a visual workflow builder for chaining LLM prompts). How do you handle rendering, zooming, panning, and connecting nodes?

#Canvas API #WebGL #Math #State Management

Practice

Frontend Engineer • System Design • medium

Design the architecture for a 'Shared Chat' feature, where a user can generate a public URL for a specific conversation. Consider security, SEO, and hydration.

#Next.js #SSR #Security #SEO

Practice

Frontend Engineer • System Design • medium

Design a robust telemetry and error tracking system for the frontend. How do you capture unhandled exceptions, promise rejections, and performance metrics without impacting the user experience?

#Observability #Error Handling #Performance

Practice

Frontend Engineer • Technical • medium

Explain the differences between WebSockets, Server-Sent Events (SSE), and Long Polling. Why does ChatGPT primarily use SSE for model responses?

#Networking #Protocols #Performance

Practice

Frontend Engineer • Technical • hard

How does React 18's concurrent rendering work? How would you use `useTransition` or `useDeferredValue` to keep a chat interface responsive while rendering a heavy Markdown response?

#React Internals #Performance Optimization #Concurrency

Practice

Frontend Engineer • Technical • medium

What are the accessibility (a11y) considerations when building a dynamically updating chat interface like ChatGPT?

#ARIA #Screen Readers #UX

Practice

Frontend Engineer • Technical • medium

Explain the JavaScript event loop, microtasks, and macrotasks. How does a heavy DOM update impact the event loop, and how can you mitigate it?

#Event Loop #Performance #Browser Architecture

Practice

Frontend Engineer • Technical • hard

How would you optimize the performance of a React application that frequently updates a large, complex SVG (e.g., a real-time data visualization of model weights)?

#React #SVG #Rendering Optimization

Practice

Frontend Engineer • Technical • medium

What are the security implications of rendering user-generated or AI-generated Markdown into HTML? How do you prevent XSS attacks in a React application?

#XSS #Sanitization #React

Practice

Difficulty Radar

Based on recent AI-sourced data.

Meet Your Interviewers

The "Standard" Interviewer

Senior Engineer

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

Simulate

Unwritten Rules

Think Out Loud

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

Practice Now