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System design interview question · Backend

Design a payment processing platform

Accept payment requests reliably without charging a customer twice.

Advanced 60 minutesTransactions Plus
More Backend questions

Concepts this round covers

  • Idempotency keys
  • State transitions
  • Reconciliation and audit
  • Transactions

This is a Plus round

The brief, the scale to design for, the questions interviewers ask and the common mistakes for this round are available to Plus members. Plus is coming soon.

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Build a service that turns long links into short, shareable URLs.

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Protect a public API without slowing down well-behaved clients.

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