Mock system design interview at Coinbase
A live 45-minute round on a question reported in Coinbase interviews, run by an AI interviewer that asks one thing at a time, probes what you say, looks at your whiteboard, and weighs what that round is reported to weigh. It ends with a debrief: a score, what was strong, what was missing.
Design a Stock Exchange
Match buy and sell orders in microseconds, in a strict and provable order, never lose a fill, and stay correct when the matching engine dies mid-trade.
You will not see the requirements, the numbers or the design before you start. That is the point.
What the Coinbase round is reported to look like
60 minutes on the architecture of a real-world service. The example Coinbase gives is a Twitter feed, and candidates also report money-shaped prompts: a ledger, a real-time crypto price service, order routing or scheduled payments.
What it weighs
- Clarifying questions: the brief is short, and pinning down the requirements is up to you
- The whole problem covered at a general level, naming a technology you know well where it fits
- Correctness where money moves: idempotency, no lost or duplicated funds, and reconciliation
- Security and consistency around balances, wallets and withdrawals
The common mistake
Going deep on one part too early. Coinbase advises keeping the design general across the whole problem unless the interviewer asks for depth, and checking with them before you finish whether anything is left to cover.
From public interview guides and candidate reports, and Coinbase’s own interview guidance where it publishes any. Not endorsed by Coinbase. The interviewer is an AI running in that style; it is practice, not a prediction.
Start the round
The interviewer’s opening question is free. Answering it is part of Pro. See an example round and its debrief →
The 4 questions this round draws from
Each is reported in Coinbase interviews. Pick one to sit, or read its reference design and walk through a strong answer first.
- Design a Stock ExchangeMatch buy and sell orders in microseconds, in a strict and provable order, never lose a fill, and stay correct when the matching engine dies mid-trade.drawn
- Design Venmo80 M users paying friends instantly: 15 M transfers a day on a sharded double-entry ledger, funded and cashed out over slow bank rails.
- Design a Fraud Detection SystemAllow, block or challenge 10,000 card payments a second in under 100 ms, then learn from chargebacks that arrive months later.
- Design RobinhoodA retail brokerage: live prices to 3 M phones, 20 k orders a second at the open, every share and cent exact.
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