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Anthropic system design interview questions

6 questions on this site are reported in Anthropic software engineer interviews. Each is a guided run through requirements, back-of-envelope numbers, an interactive design, user flows and deep dives with interviewer follow-ups. Patterns covered: real-time, websockets, fan-out, chat, ranking, caching, social, gpu-batching, streaming, scheduling, kv-cache, consistent-hashing, eviction, replication, hot-keys, frontier, politeness, dedupe, distributed-queues, algorithms, counters, redis, edge.

Run an AI mock Anthropic interview →One of these questions, run as a live round in that style, with a debrief at the end.

Attribution comes from public interview guides and candidate reports, not from Anthropic. It indicates where a question has been asked, nothing more.

🔒 Pro
hardreal-timewebsocketsfan-outchat

Design Slack

Real-time team messaging: channels, DMs, presence, history and search for millions of concurrent users.

asked at
14 components5 flows6 deep dives
AI interviewStudyPractice
not started
🔒 Pro
hardfan-outrankingcachingsocial

Design a News Feed

The home timeline of Twitter, Instagram or Facebook: posts from people you follow, ranked, fresh, and fast for hundreds of millions of users.

asked at
14 components5 flows5 deep dives
AI interviewStudyPractice
not started
🔒 Pro
hardgpu-batchingstreamingschedulingkv-cache

Design an LLM Inference Service

Serve a large language model behind an API: queue the requests, batch them onto scarce GPUs, stream tokens back, and keep every accelerator busy without blowing the latency budget.

asked at
15 components5 flows6 deep dives
AI interviewStudyPractice
not started
🔒 Pro
hardconsistent-hashingevictionreplicationhot-keys

Design a Distributed Cache

A Redis-like cache as a service: hundreds of nodes, terabytes of memory, sub-millisecond gets, and a cluster that survives losing a machine mid-request.

asked at
13 components5 flows6 deep dives
AI interviewStudyPractice
not started
🔒 Pro
hardfrontierpolitenessdedupeschedulingdistributed-queues

Design a Web Crawler

Fetch billions of pages a month politely, discover new links, skip duplicates, and keep the copy fresh without getting the crawler banned.

asked at
14 components5 flows5 deep dives
AI interviewStudyPractice
not started
🔒 Pro
mediumalgorithmscountersredisedge

Design a Rate Limiter

A distributed service that decides, in under a millisecond, whether a request from a client is allowed under its quota.

asked at
12 components5 flows5 deep dives
AI interviewStudyPractice
not started

What the Anthropic round looks like

A 50–55 minute round, often on infrastructure behind an AI product rather than a consumer app. Two shapes are reported: design from scratch, and reviewing a design document and improving it.

What it is reported to weigh

  • Decomposition: breaking an open problem into parts that can be reasoned about separately
  • Scale reasoning under real constraints, especially scarce and expensive capacity
  • Failure modes, overload behaviour and what degrades first
  • Driving the conversation yourself at staff level, rather than waiting to be prompted

The common mistake

Most of the questions reduce to ordinary distributed systems — queueing, batching, backpressure. Candidates who reach for model internals instead of the infrastructure answer tend to drift.

From public interview guides and candidate reports, not from Anthropic. Formats change; treat it as a prior, not a promise.

How to prepare for a Anthropic system design interview

Large-company loops run 45 to 60 minutes, expect numbers, and spend most of the time on deep dives. Work each question above in practice mode until you can produce the requirements, the estimates and the flows without looking, then read the interview framework guide for how to structure the hour. The other questions on the site teach patterns that show up in Anthropic interviews under different names.