Guide Maps Path from Payment Integration to Fintech Architecture Design

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A technical guide published on DEV Community outlines how developers can advance from basic payment gateway integration to designing full-scale fintech payment infrastructure. The guide uses PHP 8.x and Laravel as its implementation stack and addresses the core challenge of reconciling three asynchronous sources of truth: application state, gateway state, and bank network state. It covers payment flows including subscriptions, wallets, split payments, refunds, and chargebacks, emphasizing that refunds must be modeled as separate entities rather than status flags on a payment record. The architecture separates concerns across dedicated services — including Order, Payment, Wallet, Accounting, Webhook, and Reconciliation — with the Payment Service acting as the sole layer permitted to communicate with external gateways. A key design principle highlighted is that asynchronous, unreliable payment confirmation is the root reason behind patterns like idempotency, state machines, and webhook deduplication.

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