🏦 Finance & Banking · C4 Architecture · Pro
Payment Gateway Architecture
A payment gateway that lets online merchants accept cards and UPI: the checkout, the payment core with fraud checks, and the card networks and banks it connects to.
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Drawing diagram…
What this diagram shows
- Merchant checkout and merchant dashboard as separate front ends
- Fraud checks run before every authorisation
- Events go to Kafka for settlement, reporting and webhooks
Prompt used
A payment gateway for online merchants. Customers pay on a hosted checkout page. An API gateway routes to a payment service that calls a fraud detection service before authorising with card networks or the UPI switch. Transactions are stored in PostgreSQL and events are published to Kafka, which a settlement service and a webhook service consume. Merchants see payments in a merchant dashboard.
Mermaid code
C4Container
title Payment Gateway
Person(customer, "Customer", "Pays for an order")
Person(merchant, "Merchant", "Tracks payments")
System_Boundary(pg, "Payment Gateway") {
Container(checkout, "Hosted Checkout", "React", "Card and UPI payment page")
Container(dash, "Merchant Dashboard", "Angular", "Payments, refunds, reports")
Container(api, "API Gateway", "Envoy", "Auth and routing")
Container(pay, "Payment Service", "Java", "Authorise and capture")
Container(fraud, "Fraud Service", "Python", "Risk score per payment")
Container(settle, "Settlement Service", "Go", "Daily payouts")
ContainerDb(db, "Transactions DB", "PostgreSQL", "Payments and refunds")
ContainerQueue(bus, "Event Bus", "Kafka", "Payment events")
}
System_Ext(network, "Card Networks / UPI", "Visa, Mastercard, NPCI")
Rel(customer, checkout, "Pays on")
Rel(merchant, dash, "Uses")
Rel(checkout, api, "Calls", "HTTPS")
Rel(dash, api, "Calls", "HTTPS")
Rel(api, pay, "Routes")
Rel(pay, fraud, "Checks risk")
Rel(pay, network, "Authorises")
Rel(pay, db, "Stores")
Rel(pay, bus, "Publishes")
Rel(bus, settle, "Consumed by")Related templates
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