Low-Level Design rounds at Paytm center on real payments-domain systems — wallets, transfers, and account linking — where interviewers expect you to drive requirement clarification yourself before touching a class diagram, then justify every design-pattern choice rather than just naming one.
Problem 1Design a UPI-like Digital Wallet & Payments System
Design a system that supports multiple wallet types for a user, lets a user link one or more bank accounts, transfer money to other users, check balances, and retrieve transaction history.
- Clarify requirements yourself first — what wallet types exist, and can a user hold more than one at a time?
- Think about what a 'transfer' needs to guarantee if it fails halfway (partial debit with no matching credit).
- Be ready to justify any design pattern you reach for (e.g. why Strategy fits wallet-type variation, why a Facade helps unify the transfer API) rather than just naming one.
More LLD prompts asked at fintech/payments companies
The class design, entity list, design-pattern reasoning and follow-up discussion for these — plus the full worked solution above — are part of the Placement-Ready PYQ Kit.
2 more LLD prompts with full class designs in the full Placement-Ready PYQ Kit