FinTech

AI development Payments Done Right: Idempotency, Webhooks, and the State Machine That Stops Double Charges The payment that hurts isn't the one that fails loudly. It's the one that succeeds twice. Idempotency keys, webhook discipline, and a charge modeled as a state machine are what stop a retry or a redelivered event from charging a customer twice. Jul 2026 AI development How to Build Fintech Software in 2026 (and What's Still Standing in 2028) Most fintech products don't fail on the features. They fail on the money math, and the money math was never what the demo showed. A builder's map to what decides it: idempotent payments, an immutable ledger, reconciliation that ties out, and the moat that compounds by 2028. Jul 2026