Design an LLM evaluation platform
PremiumLLM systemMedium
- LLM as a judge
- Offline evaluation
- Golden datasets
Quick answer
This LLM system interview question asks you to design an LLM evaluation platform. Aim for a design that uses language models to serve users well, then explain retrieval, prompting, serving, evaluation and trade-offs. Interviewers want to see how you control quality, cost and latency, and how you evaluate the results.
The problem
Design an LLM evaluation platform that product teams use to test every prompt or model change before it ships. It runs test suites, scores outputs with rules, LLM judges and human reviewers, and blocks releases that regress. The hard parts are trusting the judges, staying within cost and rate limits, and telling real regressions from noise.
Today each of 40 teams tests by reading a few outputs by hand, and regressions reach users.
What must an LLM evaluation platform do?
- Suites and datasets: Teams register versioned datasets and suites with scorers: exact match, schema checks, rubric and pairwise LLM judges, and RAG faithfulness and citation checks.
- Release gates: A pull request that changes a prompt or model runs its suites, compares with the current baseline and blocks the merge on a significant regression.
How well must it do it?
- Trustworthy scores: A judge may gate releases only after it agrees with human labels on at least 85% of cases, with Cohen's kappa of at least 0.6.
- Speed: A pull-request gate finishes within 15 minutes.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- LLM as a judge
- Offline evaluation
- Golden datasets
- Human review
- Regression testing
- Judge calibration
How you’ll practise
- Problem framing
- Data and retrieval
- Prompting and orchestration
- Evaluation and safety
- Serving, cost and latency
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any LLM system design round.
- Defines the user task and what a good answer is
- Explains how relevant context reaches the model
- Plans evaluation before and after launch
- Controls cost and latency with caching and routing
- Covers safety, privacy and abuse
- Handles failures and fallbacks gracefully
Questions people ask about this interview question
- Which design type is this question?
- It is an LLM system question. You design an LLM evaluation platform and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Medium. Entry-level engineers can practise it, but it expects you to reason about requirements and trade-offs, not only list components.
- What should I cover first?
- Start with the user task, what a good answer looks like and how it will be measured. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
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Updated · Written by the SevyDevy team