Design a Payment Processing System (Stripe / PayPal)
Guarantee zero money loss: Idempotency keys, Double-entry bookkeeping ledger (immutability), Reconciliation pipelines, and PCI-DSS vault tokenization.
01.Functional & Non-Functional Requirements
A Payment Processing Platform (Stripe, Adyen, PayPal) processes financial transactions, communicates with acquiring banks and card networks, manages merchant payouts, and guarantees zero monetary loss.
Functional Requirements
- Pay-in (Charge Processing): Accept credit card/bank payments from buyers and charge merchant accounts.
- Pay-out (Disbursements): Transfer accumulated merchant balances to external bank accounts.
- Card Tokenization (PCI Compliance): Tokenize sensitive Primary Account Numbers (PAN) into secure non-PCI tokens (
tok_18a94b2). - Double-Entry Bookkeeping Ledger: Maintain an immutable financial ledger where every credit has a balancing debit.
- Nightly Settlement Reconciliation: Reconcile internal ledger transactions against external bank clearing files.
Non-Functional Requirements
- Zero Double-Charge Guarantee (Strict Idempotency): Duplicate requests must never result in duplicate credit card charges.
- Data Integrity & Immutability: Financial ledger entries can never be modified or deleted.
- High Availability & High Consistency:
99.999\%uptime with strong ACID guarantees on ledger commits. - PCI-DSS Level 1 Compliance: Sensitive cardholder data must be quarantined in an isolated, encrypted vault.
Stripe-Style Payment Gateway & Double-Entry Ledger Architecture 💳
Stripe-Style Payment Gateway & Double-Entry Ledger Architecture 💳
PCI-isolated tokenization vault, idempotent payment state machines, immutable double-entry bookkeeping ledger, and nightly bank settlement reconciliation.
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