Design a Payment System: Holds and Captures, Batch Charges, Reconciliation, Idempotency
Company: OpenAI
Role: Software Engineer
Category: System Design
Difficulty: hard
Interview Round: Onsite
Overview: Design a payment system that places holds and captures final amounts, submits charges in batches, reconciles internal records against processor settlement reports, and never double-charges when calls are retried. It tests payment state machines, double-entry ledgers, idempotency and reconciliation.