Sales
Practice
PRO
Anti-Fraud: Chargebacks and Multi-Accounts
Money leaks from any selling service three ways: a payment bug gives a double grant, one access is handed out to a crowd, and trials and promos get abused from multi-accounts. All three holes are closed procedurally. I show how — with concrete fields and rules.
Hole 1. Double grants (idempotency)
The most frustrating leak: the customer paid once but got two terms. Why it happens — providers do webhook retries (that's normal), plus the customer can hit "pay" twice. Without protection, every repeat = an extra free term.
How I close it:
- A unique index on
txid/invoice_id/order_id in the database. A repeat webhook with the same id — silently ignore: return 200, grant nothing.
- The webhook responds
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