What Happens When You Open a URL
A browser first resolves an address, creates a protected connection, receives HTML, discovers CSS, JavaScript, images, and other dependencies, and finally constructs a screen. The server doe...
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System Design
Notes on product engineering, fintech systems, learning, and the decisions behind the work.
- Production systems
- Product decisions
- Engineering craft
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From Send to Read—What a Messaging App Does
A chat bubble usually does not travel directly to someone else's screen. The sender's device, the service's servers, push-notification infrastructure, and the recipient's devices cooperate....
How Email Actually Works—from Send to Inbox
Email is not a message fired directly at someone else's phone. It is a store-and-forward system: servers act like post offices that look up an address, accept the message, relay it, and plac...
From Vibe Coding to Production Engineering
AI has significantly lowered the barrier to building software. A few years ago, if you wanted to build an app or service, you had to learn a programming language, understand a framework, rea...
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External API Integration Is Harder Than It Looks
External API integration often looks simple at first. You read the documentation, find the endpoint, build a request, send it, receive a response, and update your system. With AI coding tool...
