Designing a Settlement System
Settlement is the part of a payments business that nobody talks about and everybody fights about in production. It is the machinery that takes the noisy stream...
11 min359Read →
Tagged #payments
13 articles tagged #payments.
Tokenization vs Encryption for Card Data
Every few months a product manager or a board member asks me some version of the same question: "We encrypt the card numbers, so we are PCI compliant and safe,...
11 min441Read →
Understanding Webhook Signatures
Almost every fintech integration I have shipped eventually grows a webhook surface. Card networks, payment processors, KYC vendors, ledger systems, and...
10 min431Read →
Building Multi-Currency Support
Every payments platform reaches a moment where a single currency stops being enough. For us it arrived the day a logistics customer in France asked whether...
10 min795Read →
An Engineer's Introduction to PCI DSS
Every engineer who touches a payments system eventually runs into PCI DSS, usually at the worst possible moment: a few weeks before a deadline, when someone in...
11 min368Read →
Building a Reconciliation Engine
Every payments company eventually runs into the same uncomfortable truth: the money you think you have and the money you actually have are two different...
11 min589Read →
An Introduction to Double-Entry Ledgers in Software
Every few years a new engineer joins one of my teams, looks at our ledger code for the first time, and asks the same question: why are there two rows for every...
11 min1004Read →
Handling Money in Code: Never Use Floats
Every engineer who has spent time near a payments ledger eventually learns the same lesson, usually at the worst possible moment: a reconciliation report is...
10 min870Read →
Idempotency Keys Explained Simply
Every payments engineer eventually meets the same ghost. A customer taps "Pay" once, the network hiccups, the mobile app retries on their behalf, and suddenly...
11 min1017Read →
Designing Webhooks That Survive Failure
Webhooks are the part of a payments platform that everyone treats as an afterthought until the night they take down a customer's order pipeline. They look...
11 min866Read →
Observability for Payment Systems: Logs, Metrics, and Traces That Matter
When a payment fails at 2am, the question is never "is something wrong." Your customers have already told you that, loudly, across every channel you have. The...
4 min703Read →
Event-Driven Architecture for Cross-Border Payments: A Practical Primer
Cross-border payments are a sequence of steps that happen at different speeds, controlled by different parties, any of which can fail independently and at the...
5 min936Read →