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OpenAI API & ChatGPT Interview Questions Interview Guide

10 interview questions with sample answers

8-12 hours
Prep Time
$160K-$230K
Salary
10
Questions

About This Role

Interview prep for roles building with OpenAI API, GPT models, fine-tuning, and deploying LLM applications at scale.

Behavioral Questions (3)

Q1

Tell me about a production system you built with OpenAI APIs. What did you optimize for?

Sample Answer:

I built a customer support chatbot using GPT-4, optimizing for accuracy over speed. I implemented guardrails to prevent misuse, logged conversations for feedback loops, and achieved 85% customer satisfaction.

Q2

How do you handle API costs in production at scale?

Sample Answer:

I analyzed usage patterns, implemented response caching for common queries, routed simple requests to GPT-3.5-turbo, reserved GPT-4 for complex problems. Reduced costs by 65% without quality loss.

Q3

Describe a situation where you had to use fine-tuning. Why not prompt engineering?

Sample Answer:

For domain-specific classification, fine-tuning beat prompting by 12% accuracy. The task had subtle patterns that examples couldn't capture. Fine-tuning cost $1200 but saved engineering time and improved reliability.

Technical & Situational Questions (4)

Q4

How do you design a system to automatically route requests between GPT-3.5-turbo and GPT-4?

Sample Answer:

Classify task complexity using heuristics or lightweight model, route simple queries to 3.5-turbo, complex to GPT-4. Monitor latency and quality, adjust thresholds weekly. Cache GPT-4 results aggressively.

Q5

Explain how function calling works in OpenAI API and when you'd use it.

Sample Answer:

Function calling lets models request specific actions, enabling multi-step workflows. Use for: data retrieval, calculations, database operations. Chain multiple function calls for complex tasks.

Q6

How do you implement reliable streaming responses in a web app?

Sample Answer:

Stream tokens to client as they arrive, render progressively, handle connection drops with retry. Store all streamed content server-side for logging and recovery.

Q7

What's your approach to fine-tuning data preparation?

Sample Answer:

Curate high-quality examples (500+ minimum), format consistently, validate outputs manually, split 80/20 train/val, monitor validation loss for overfitting, iterate based on results.

FAQ

When should I fine-tune vs use prompt engineering?
Fine-tune for: domain-specific patterns, style consistency, complex multi-step reasoning. Use prompting for: general tasks, one-time customization, rapid iteration.
How do I estimate OpenAI API costs?
Calculate tokens per request, multiply by model pricing, account for prompting overhead (5-20%). Monitor actual usage weekly, implement caching and routing to optimize.
What's the best way to handle API rate limits?
Implement token bucket rate limiting on client, exponential backoff on 429 errors, batch requests where possible, use lower-cost models for spillover traffic.
How do I ensure responses don't leak sensitive data?
Never log sensitive data, use system prompts to restrict outputs, implement input validation, audit access logs monthly, train users on prompt injection risks.

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Last updated on 2026-03-07