Core Banking

Prerequisite: Read Executive Summary: Core Banking Developer Roadmap for architectural context. Double-Entry Bookkeeping: Core Banking Ledger Guide Answer-first: Double-entry bookkeeping in core banking guarantees that every transaction records equal and offsetting Debit and Credit entries across sub-ledgers. By enforcing $\sum \text{Debits} = \sum \text{Credits}$ at the database schema level via atomic multi-leg constraints (CHECK (sum(amount) = 0)) and immutable append-only journal structures, financial engineering engines eliminate balance drift, rounding loss, and audit discrepancies under high transaction concurrency. ...

Prerequisite: Read Part 1: Double-Entry Bookkeeping for ledger schema and balance invariant fundamentals. Core Banking Domain Modeling: CIF, CASA & Lending Guide Answer-first: Core banking domain architecture revolves around three fundamental bounded contexts: Customer Information File (CIF) for identity management and KYC compliance, Current & Savings Accounts (CASA) for high-velocity transactional deposit ledgers, and Lending for multi-period credit amortization. Decoupling these domains into autonomous Go microservices communicating via gRPC contracts eliminates database lock contention between daytime retail transactions and nightly End-of-Day (EOD) interest accrual batch jobs. ...

Core Banking Systems Architecture Masterclass Guide Answer-first: Modern cloud-native core banking transitions from batch-driven mainframes to composable distributed platforms: immutable double-entry ledgers enforcing mathematical zero-drift balance invariants, multi-region Distributed SQL guaranteeing serializable ACID transactions, event-sourced CQRS projections, orchestrated compensation Sagas, zero-allocation ISO 20022 streaming, and FAPI 2.0 security. This architecture eliminates end-of-day batch freezes, delivering sub-25ms P99 latency across active-active deployments. Prerequisite: Practical familiarity with distributed systems fundamentals, relational transaction isolation levels (ACID), event-driven microservice patterns, and enterprise networking (mTLS, TCP/IP, gRPC). For foundational context, explore our Banking Microservices Architecture and Go Microservices Guide. ...