Guides
Payments, explained one problem at a time.
Free extracts from the 42-chapter book. Each guide answers one question completely, with the diagrams and code from the chapter it came from, and the glossary defines all 193 terms. No email required.
Guides
Payment lifecyclesThe payment states every provider has, whatever they call themA payment is a state machine, not an API call. The states every provider shares, what goes wrong at each one, and why one-call thinking causes 3 AM bugs.WebhooksWebhooks arrive twice, out of order, or neverWhy re-serialising a payload breaks signature verification, and how to build a handler that survives duplicates, replays and out-of-order delivery.ComplianceHow much PCI DSS actually applies to youPCI scope depends on whether card data touches your servers, not your size. What the levels mean and how tokenisation removes most of the burden.Fees and marginWhat card payments actually cost youThe headline rate is never the whole bill. How interchange, scheme fees and markup stack up, and which add-ons quietly change your effective rate.
The whole thing
The guides are the parts. The book is the system.
Eight providers with their fees in the open, then fraud, reconciliation, scaling and compliance. Every example is Python with the error handling left in.
42chapters
1,000+pages
90+Python examples
30-day money-backInstant PDF and EPUB
