Blog & insights.
Writing from our founder, Anselm Fowel — on fintech, engineering leadership, product craft, and building at scale. Articles live on anselmfowel.com and stream in here as they are published.
Leading a Team Through a Painful Migration
The Slack message came in at 6:42 on a Tuesday morning. One of my senior engineers, a person who almost never messages before nine, had written a single line:...
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Building an Idempotent Refund Flow
The first time a refund double-fired in production, it cost us about 4,200 euros before anyone noticed. A merchant's support agent clicked the refund button,...
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How to Handle a Toxic High Performer
The first time I got this badly wrong, I kept a senior engineer for fourteen months longer than I should have because his throughput was extraordinary. He...
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The Saga Pattern for Distributed Transactions
A few years ago I watched a payout run leave forty-two merchants with money debited from our settlement account but never credited to their bank. The culprit...
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Presenting a Technical Roadmap to Executives
The first technical roadmap I ever presented to a board lasted four slides before the CFO stopped me. I was three minutes into explaining why we needed to...
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Handling Partial Failures in Distributed Systems
A payment either happens or it doesn't. That's the story we tell customers, and it's the story regulators want to hear. But underneath, a single card...
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Managing a Team That Is Smarter Than You
Early in my time running engineering at a payments company, I sat in a design review for a ledger rewrite and realized, about ten minutes in, that I could not...
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Why We Chose PostgreSQL Over a NoSQL Store
The meeting that decided this ran about forty minutes. We had a greenfield ledger service to build, a payments platform that would eventually touch a few...
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Why Your Best Ideas Come From Junior Engineers
Three years ago, a graduate engineer named Priya asked me why our payment reconciliation job ran every fifteen minutes. She had been with us for six weeks. The...
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