Start free
interview prep for software engineers

Crack the AI infra system design interview.

Watch a real mock interview. Answer each hard question, then see the staff-level answer.

Watch a free interview → no ML background needed ✓

problems reported from OpenAI · Anthropic · Perplexity

Design ChatGPT · 11:26
MeiArjun
Mei, the interviewer, asks:

A worker freezes. Another takes over. Then the first one wakes up. What now?

The best way to prep for AI infra.

only AI infra

LLM serving, GPU scheduling, RAG, agents, evals.

No URL shorteners with AI sprinkled on top.
this month's problems

Dated and sourced from candidate reports.

Updated as new reports come in.
the real interview

Full mocks you pause and answer.

With the mid, senior and staff answer.

What carries over, and what's new.

AI infra is distributed systems with a model in the middle

what you knowwhat it becomes in AI infra
Load balancingrouting to GPU replicas
Queues and backpressurecontinuous batching
Cachingthe KV cache
Rate limitingtoken budgets
Leases and idempotent writesfencing a frozen GPU worker

new to learn: tokens · KV cache · GPU memory · batching · evals

what AI loops are asking now

    See the bar for your level.

    The finished whiteboard from Design ChatGPTyours to edit ↗
    free · watch now

    Design ChatGPT

      Costs less than one hour with a coach.

      expense it → or start free →

      Questions

      Who is it for?

      Software engineers (backend, infra, platform, full-stack) going after AI engineer and AI infrastructure roles, from mid to staff. Each interview is broken down for every level.

      Do I need an ML background?

      No. AI infra rounds are distributed systems with a model in the middle, so most of what you know carries over: load balancing, queues, caching, rate limits, streaming, idempotency. What's new is a short list: tokens and context windows, the KV cache and GPU memory, batching, retrieval and evals. The interviews teach those as they come up, on top of what you already know.

      Who are Mei and Arjun?

      Our interviewer and candidate. Every interview is written by us from candidate reports, reviewed, and produced with AI voices, which is how we ship new problems and every level of each.

      Does it renew automatically?

      Monthly renews until you cancel. Yearly renews once a year, and we email you 7 days before it does. If you subscribed during an offer, you keep that price for as long as you stay subscribed. Lifetime is paid once. Any plan: full refund within 30 days of your first payment, no questions asked; just reply to your receipt.

      How long is the offer on?

      Pro is $79/year and lifetime $199 for a limited time; the bar at the top shows exactly how long you have. When it ends, it's $119/year and $299 lifetime for you, and it doesn't come back. Get Pro before then and you keep your price for as long as you stay subscribed. Monthly is always $39.

      Can my company pay?

      If your employer reimburses professional development, use "expense it" under the plans: it opens a short note to your manager with the price and the refund terms.

      See where your answer lands