5 min read
The Card Fee a Refund Doesn’t Give Back
I tracked a $10 refund, cent by cent.
From checkout to payout
I build payment systems growing businesses can trust.
Consultant
Billing & PaymentSoftware Engineer
ChartVPS Technologies
Recent writing
Notes from the work
7 min read
The Life of One Subscription
A promise, three bills, one declined card, and a cancel that did not cut anyone off.
8 min read
The Price That Lived in Two Places
The page said 30 dollars. The card was charged 35. Nobody lied.
Consultancy
How I build billing
Money is an integer with a currency
Amounts are whole numbers in cents, always with the currency. No floats, no cent-off invoices.
Webhooks arrive more than once, and out of order
Events can repeat or arrive late. I verify each one and skip any I've already handled.
Provider owns the money, my database owns the access
Stripe knows who paid, my app decides who gets in, and a scheduled check keeps them in sync.
Every retry is safe
Every payment request has a unique key, so a retry or double-click never charges twice.