Payment Systems
Architecture and reliability guidance for gateways, switches, card flows, authorization, reconciliation, cryptographic boundaries, and highly available financial services.
Payment Switch Architecture: How Financial Transactions Are Routed Reliably
A practical payment-switch architecture covering channels, routing, HSMs, state, queues, timeouts, reversals, reconciliation, monitoring, and high availability.
7 min readCard Payment Transaction Flow: From POS Terminal to Issuer and Back
Follow a card payment from cardholder and terminal through merchant, acquirer, switch, network, issuer, clearing, and settlement.
6 min readIssuer vs Acquirer: Roles in Card Payment Processing
Compare issuers and acquirers across customers, risk, authorization, merchant acceptance, settlement, disputes, and system responsibilities.
8 min readHow Payment Gateways Work: Architecture, APIs, Security and Reliability
Understand gateway architecture from checkout and APIs through processors, switches, issuers, webhooks, idempotency, and reconciliation.
6 min readPayment Reversal Flow: Recovering Timed-Out Financial Transactions
Design application-level and switch-level reversal handling for unknown outcomes, late responses, duplicates, and reconciliation.
6 min readAuthorization, Clearing and Settlement Explained
Understand the distinct goals, timing, records, and failure modes of payment authorization, clearing, and settlement.
6 min readHardware Security Modules in Payment Systems: What Software Engineers Need to Know
A defensive guide to HSM key isolation, PIN processing, cryptographic operations, key lifecycle, integration boundaries, and audit.
7 min readPayment Reconciliation: Matching Transactions, Settlement and Exceptions
Design reconciliation across an internal ledger, processor reports, settlement files, duplicates, missing records, and exception workflows.
6 min readHigh-Availability Payment Systems: Reliability and Disaster Recovery
Plan load balancing, redundancy, failover, databases, queues, health checks, observability, disaster recovery, RTO, and RPO.