🏦 Finance & Banking · C4 Architecture · Pro
Core Banking System Architecture
The main building blocks of a bank's core platform: accounts, deposits, loans, payments and the general ledger, used by branches, internet banking and mobile.
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Drawing diagram…
What this diagram shows
- All channels go through one API layer
- Every money movement posts to the general ledger
- Payment rails (UPI, NEFT, RTGS) connect through a payments hub
Prompt used
Core banking architecture: customers use mobile and internet banking, staff use a branch system; all call an API layer. Core services: customer (CIF), accounts and deposits, loans, payments hub (UPI, NEFT, RTGS, IMPS), and the general ledger that receives every posting. Data in Oracle. External: NPCI and RBI payment systems, credit bureau and the regulatory reporting system.
Mermaid code
C4Container
title Core Banking System
Person(customer, "Customer", "Mobile and internet banking")
Person(teller, "Branch Staff", "Counter operations")
System_Boundary(cbs, "Core Banking") {
Container(channels, "Digital Channels", "Mobile / Web", "Accounts, transfers")
Container(branch, "Branch System", "Web", "Teller and back office")
Container(api, "API Layer", "Java", "Auth and routing")
Container(cif, "Customer (CIF)", "Java", "Customer master, KYC")
Container(acct, "Accounts and Deposits", "Java", "Savings, current, FD")
Container(loans, "Loans", "Java", "Disbursal and EMIs")
Container(payhub, "Payments Hub", "Java", "UPI, NEFT, RTGS, IMPS")
Container(gl, "General Ledger", "Java", "Double-entry postings")
ContainerDb(db, "Core DB", "Oracle", "Accounts and transactions")
}
System_Ext(npci, "NPCI / RBI Systems", "Payment rails")
Rel(customer, channels, "Uses")
Rel(teller, branch, "Uses")
Rel(channels, api, "Calls")
Rel(branch, api, "Calls")
Rel(api, acct, "Routes")
Rel(api, loans, "Routes")
Rel(api, payhub, "Routes")
Rel(acct, gl, "Posts")
Rel(loans, gl, "Posts")
Rel(payhub, npci, "Settles")
Rel(acct, db, "Stores")Related templates
UPI Payment Flow
The steps behind a UPI payment: the payer's app, the payer's bank, NPCI's UPI switch and the payee's bank, from entering a UPI ID to the money arriving.
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.
Loan Origination Workflow
A personal loan from application to disbursal: KYC, credit bureau check, underwriting rules, manual review for borderline cases, and the final agreement.
Card Payment Authorisation
What happens in the second after a card is tapped or entered online: the acquirer, card network and issuing bank authorise the payment, with 3-D Secure for online payments.
Real-Time Fraud Detection Data Flow
How a bank scores every transaction for fraud in milliseconds: features from history, an ML model, rules, and a case queue for analysts.
Digital KYC Onboarding
How a bank or fintech opens an account fully online: Aadhaar/PAN verification, video KYC, risk checks and account creation.