OpenAI API & ChatGPT Interview Questions Interview Guide
10 interview questions with sample answers
About This Role
Interview prep for roles building with OpenAI API, GPT models, fine-tuning, and deploying LLM applications at scale.
Behavioral Questions (3)
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.
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.
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)
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.
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.
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.
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?
How do I estimate OpenAI API costs?
What's the best way to handle API rate limits?
How do I ensure responses don't leak sensitive data?
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