Payment API integration: a developer's guide
Payment API integration means connecting your application to a payment provider so it can authorize, capture, refund, and reconcile money. Getting the first charge to succeed is the quick part, and the reliability comes from how you handle everything that follows: duplicate requests, missed webhooks, declines, and the gap between what your database believes happened and what actually settled.
I run Milo Solutions, and my team has built payment flows from scratch and been called in to fix ones that were quietly losing money, and that money rarely drains away at the checkout screen itself. Card fraud losses worldwide reached $33.41 billion in 2024, with the United States accounting for 41.87% of those losses despite generating just 26.31% of global card volume, according to the Nilson Report [2]. Almost all of the US total is card-not-present fraud, the kind that happens on exactly the sort of online payment you're about to build, so most of the risk and most of the engineering sit in your code rather than on the provider's hosted page.
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