Articles
Plain explanations of how payment systems work and how to architect them, and practical notes on moving into engineering leadership.
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Architecture
Idempotency and retries: why payments get charged twice
How a lost reply turns a safe retry into a double charge, how idempotency keys prevent it, and the details that decide whether they work.
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Architecture
What 99.9% availability actually takes in a payment system
The downtime budget, why dependencies multiply against you, and the design, release and operations habits that keep payments up.
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Payments
How a card payment works, from tap to settlement
The five parties, the message they pass around, who earns what, and why payments fail.
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Payments
How UPI moves money in seconds
What happens between scanning a QR code and hearing the soundbox, and where your PIN goes.
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Careers
From developer to manager: what actually changes
The shift in how your work is measured, and five interview questions to prepare for.