Fintech Interview Guide: Payments, Crypto & Banking

Fintech Interview Guide: Engineering Financial Systems

Fintech companies like Stripe, Square, Plaid, and Robinhood combine software engineering with financial domain expertise. Interviews test distributed transactions, real-time processing, regulatory compliance (PCI-DSS, SOX, KYC/AML), and high-availability system design. Fintech engineers earn 15-25% premiums over equivalent roles in non-financial tech.

The most common fintech interview question: "Design a payment processing system." This tests idempotency, distributed transactions, double-entry accounting, and PCI compliance — all in one question.

Key Fintech Concepts

• Double-Entry Accounting — Every transaction creates a debit and credit entry. Fundamental for financial system design
• Idempotency — Payment requests must be safe to retry. Use idempotency keys (UUID per request)
• PCI-DSS Compliance — Never store raw card numbers. Tokenization, encryption, network segmentation
• Real-Time Processing — Sub-second authorization, fraud detection at transaction time
• Reconciliation — Daily batch reconciliation between internal ledger and bank records

For system design preparation: fundamentals guide. For Stripe specifically: Stripe interview guide.