How We Run Blue-Green Deployments
The first time I ran a blue-green deployment in anger, it was 6:40 on a Friday evening and the payment authorization service had been down for eleven minutes....
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Tagged #fintech — Page 2
The Case for Boring Technology in Fintech
A few years ago I sat in a postmortem for an outage that cost us most of a business day of failed settlements. The root cause was not a bug in anything we had...
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Building a Rules Engine You Can Actually Maintain
The worst rules engine I ever inherited had 1,847 rules in a single database table, evaluated top to bottom, and the order they ran in was determined by the...
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What a Decade in Fintech Taught Me
When I started in fintech, the word itself still carried a faint whiff of novelty. We were the upstarts, the people building software around the edges of banks...
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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 →
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,...
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Designing for Audit Trails from Day One
Every fintech founder I have worked with eventually has the same uncomfortable conversation with an auditor, a regulator, or a partner bank's risk team. The...
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Understanding Webhook Signatures
Almost every fintech integration I have shipped eventually grows a webhook surface. Card networks, payment processors, KYC vendors, ledger systems, and...
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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...
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Building a Fraud Detection Pipeline
Fraud detection is one of those problems that looks deceptively simple from the outside. Someone makes a payment, you decide whether it is legitimate, and you...
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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...
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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...
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