PhonePe's HLD rounds lean toward fintech-flavored systems — settlement, reconciliation, and consumer-scale services — over generic "design Twitter" templates. Interviewers reward requirements gathering first, since several candidates report the round going sideways specifically because scope wasn't pinned down early.
Problem 1Design a Merchant Settlement System
Design a settlement system that pays merchants out on a T+1 cycle: it must apply commission deductions, batch transactions into a settlement run, and keep a reconciliation-ready ledger of every payout.
Requirements to clarify first
- Is settlement one payout per merchant per day (net of commission and refunds), or can a merchant have several settlement accounts or currencies?
- How is commission defined — a flat percentage per merchant, or a rule set by payment method, ticket size and merchant tier — and does it change retroactively?
- How far can the T+1 run slip before it is a breach: is a settlement finishing at 6 AM instead of 2 AM acceptable, and can a merchant request an on-demand payout outside the cycle?
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The full architecture, data model, and failure-handling discussion for these are part of the Placement-Ready PYQ Kit.
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