A field guide for engineers
Banking systems,
explained for the people who build them.
What each product is really about, the invariants you must never break, the anti-patterns that cost the most, and the standards that keep systems correct.
Product groups
Moving money between parties — domestic rails, cross-border correspondent banking, direct debits, and the message standards (MT/MX, ISO 20022) that carry them.
Corporate liquidity structures — physical sweeping, notional pooling, virtual accounts, standing orders — that move or offset balances so a treasurer's cash works efficiently.
The foundational ledger every other product posts to — balances, postings, position keeping, and reconciliation. Not a product you sell; the platform everything else depends on.
The account and lending products themselves — current and savings accounts, term deposits, corporate and consumer loans, mortgages, and overdrafts.
Issuing and acquiring — credit and debit card products, merchant acquiring, and the authorise / clear / settle lifecycle behind every card transaction.
Instruments that finance and de-risk trade — letters of credit, guarantees, documentary collections, factoring, and supply-chain finance.
Post-trade securities services — custody, clearing and settlement, and corporate actions — plus the market operations that support trading.
How clients get in and how they connect — KYC onboarding, and the digital channels, host-to-host files, and open APIs they transact through.
How the bank prices and charges — relationship-based pricing, tariffs, fee schedules, and revenue assurance.
How the bank measures and controls what it might lose — credit decisioning, limits and collateral, plus market, liquidity and operational risk — fed by positions from every other system.
Keeping bad money out and staying within the rules — KYC/CDD, sanctions and watchlist screening, AML transaction monitoring, fraud detection, and the regulatory reporting that proves it.
The front office and the bank's own book — FX, money-market and derivatives dealing and booking — plus treasury, asset-liability management and funds-transfer pricing.
The tail of the lending lifecycle — delinquency and dunning, hardship and restructuring, write-off and recovery — where a souring loan is worked back to cash or closed out.
The bank's own books and what it must file — general ledger and financial close, management reporting, and regulatory returns (Basel capital and liquidity, local central-bank reporting).
Who the bank's customers are and how it serves them — the party master and single customer view, relationship hierarchies, servicing and case management, consents and preferences.
Growing and protecting client wealth — advisory and discretionary portfolio management, funds and unit-trust distribution, and bancassurance — sitting beside the core bank.