System Desgin
AI Code Reviewer in GitHub Actions: 2026 Guide
TL;DR – Native GitHub CodeQL misses semantic bugs that LLMs can spot. – Choose between local LLM inference and managed API with a decision…
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System Desgin
27 articles
Backend Dev
From PR to Production: How Kubernetes Deployments Actually Work (Single Service + Microservices in the Real World)
Most developers know how to write code. Fewer understand what actually happens after they click “Merge Pull Request.” And even fewer truly understand what…
Backend Dev
Why Your Node.js App Is Fast Locally but Slow in Production
A senior engineer’s deep dive into performance illusions, real bottlenecks, and hard-earned lessons If you’ve shipped a Node.js service to production, you’ve almost certainly…
Backend Dev
Idempotency Explained: How to Design Safe APIs That Don’t Break in Production
Idempotency is one of those topics that looks simple on paper and brutal in production. Most engineers understand the definition. Fewer understand the failure…
Backend Dev
Sprite Sheets in Node.js: How Video Platforms Show Fast Hover Previews Without Loading Hundreds of Images
Modern users don’t think in milliseconds — they think in feel. If a UI feels slow, it’s broken. And one of the most obvious…
Backend Dev
Stateless vs Stateful Services (With Real Examples)
If you’ve worked on backend systems long enough, you’ve probably heard this advice: “Make your services stateless.” It sounds simple. It sounds correct. And…
Backend Dev
Bloom Filter in Express.js (With Real Example and Dry Run Explained)
🧠 What is a Bloom Filter? A Bloom Filter is a probabilistic data structure used to test whether an element might be present in…
Backend Dev
Designing a Scalable URL Shortener: Snowflake IDs, Base62 Encoding, and Microservices
URL shorteners like Bit.ly or TinyURL are deceptively simple: take a long URL, generate a short one, and redirect. But when you want to…
Backend Dev
Designing a High-Concurrency Flash Sale Stock & Inventory Reservation System with Node.js, Redis, Lua, and MongoDB
Designing a High-Concurrency Flash Sale Stock & Inventory Reservation System with Node.js, Redis, Lua, and MongoDB