System Design
#01 Observability

Logs That Lie Free

The dashboard says everything is green. Users are screaming on Twitter. You have terabytes of logs but zero visibility into what's actually failing.

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#02 System Design

One User, One Million Followers: The Fanout Problem Nobody Warns You About Free

A celebrity signs up. Their first post triggers a write to 1 million inboxes in real time. Your architecture was never designed for this. Here's how to fix it.

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#03 Latency

The 200ms Promise: How to Rescue an API That's Bleeding Latency Premium

Your PM demos the app to investors. Every API call takes 2 seconds. You have one weekend to fix it. Here's exactly where to look and what to do.

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#04 Api

How to Design APIs That Never Break Their Clients Free

A deep dive into API versioning, backward compatibility, and evolution strategies - so you can ship confidently without waking up to angry users at 2am.

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#05 Scalability

The 3 AM Black Friday Meltdown: How to Design Auto-Scaling That Actually Works Premium

Your flash sale just went live. Traffic spiked 50x. The monolith is melting. Here's the architecture that saves you before it happens.

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#06 Database

The Database Is the Bottleneck. Always. Premium

CPU is 10%. RAM is fine. But the DB has 8,000 connections and is sweating. One missing index and one N+1 query and the whole system chokes.

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#07 Concurrency

The Ghost Writes Twice: Concurrent Updates and Silent Data Corruption Premium

Two services updated the same record simultaneously. One wins. The other silently loses. No error, just wrong data discovered three weeks later.

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#08 Microservices

The Microservice That Knew Too Much: Breaking Circular Dependencies Free

You split the monolith into 12 services. But service B calls A, which calls C, which calls B again. A circular dependency wrapped in JSON.

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#09 Zero Downtime

Deploy at 4:59 PM on a Friday: Zero-Downtime Deployments That Actually Work Premium

A senior engineer pushes a small fix right before the weekend. By 5:05 PM the on-call phone rings. Zero-downtime deployments suddenly matter a lot.

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#10 Databases

Schema Changes Without Downtime: The Art of Zero-Disruption Migrations Premium

How to evolve your database schema safely in production without taking your app offline - strategies, patterns, and real examples.

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#11 Reliability

The Inbox & Outbox Pattern Free

How distributed systems guarantee message delivery without losing your mind - or your data.

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#12 Jwt

Build JWT Auth System at Production Scale Premium

A production-grade deep dive into designing a complete JWT authentication system: architecture, login flow, request verification, token rotation, key management, and security hardening.

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#13 Redis

Rate Limiting Algorithms with Redis Free

A practical breakdown of three rate limiting algorithms - Fixed Window, Sliding Window, and Token Bucket - with plain-language explanations, Redis-backed Node.js implementations, and a trade-off comparison to help you pick the right one.

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#14 Distributed Systems

Designing a URL Shortener Free

A deep dive into designing a scalable URL shortening service like bit.ly - covering hashing strategies, storage, redirection, and analytics.

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