Real-world architecture

Case studies built for deep reading

These long-form breakdowns now use a consistent framework with requirements, APIs, HLD, LLD, scaling challenges, trade-offs, visual sections, and takeaways.

System DesignAdvanced

Database Sharding Part 7: Case Study - Scaling Discord to Billions

We have spent the last 6 parts of this series exploring the theoretical mathematics, routing algorithms, and migration playbooks for distributed databases. Now, it is time to look at one of the most famous real-world imp…

Apr 20, 20267 min read

Case StudyDatabase Sharding Mastery

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System DesignAdvanced

Distributed Transactions Part 7: Case Study - The Global Fintech Ledger

Part 7: Case Study - The Global Fintech Ledger Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. This final part brings the full series together using a realistic f…

Apr 20, 20268 min read

Case StudyDistributed Transactions Mastery

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System DesignAdvanced

Multi-Region DR: Warm Standby vs Active-Active

Multi-Region Disaster Recovery (DR) Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. If a complete AWS region goes down, your system must keep running. Designing f…

Apr 20, 20268 min read

Case StudyReliability Engineering Mastery

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System DesignAdvanced

System Design: Designing a Collaborative Editor (Google Docs)

Designing a collaborative editor like Google Docs or Notion is one of the most technically challenging system design problems. It requires synchronizing the state of a document across multiple users in real-time, even wh…

Apr 20, 20268 min read

Case StudySystem Design Interview Mastery

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System DesignAdvanced

System Design: Designing a Content Moderation System (Meta/TikTok Scale)

System Design: Designing a Content Moderation System Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. With billions of users uploading content every minute, platfo…

Apr 20, 20268 min read

Case StudySystem Design Interview Mastery

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System DesignAdvanced

System Design: Designing a Distributed Task Scheduler

System Design Masterclass: Designing a Distributed Task Scheduler Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. Every backend engineer has written a cron job. I…

Apr 20, 20267 min read

Case StudyBackend Systems Mastery

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System DesignAdvanced

System Design: Designing an E-commerce Checkout System

An e-commerce checkout system is the most critical part of any retail platform. It must handle high concurrency during flash sales, ensure that inventory is never over-sold, and integrate securely with third-party paymen…

Apr 20, 20268 min read

Case StudySystem Design Interview Mastery

#databases#system-design

System DesignAdvanced

System Design: Designing Multi-Region Active-Active Architectures

Multi-Region Active-Active: The Global Scale Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. Deploying to multiple regions is the only way to survive a total regi…

Apr 20, 20266 min read

Case StudyReliability Engineering Mastery

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System DesignAdvanced

System Design: Designing an Object Store (Amazon S3 Internals)

System Design: Designing an Object Store (Amazon S3) Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. An Object Store is a distributed storage system designed to s…

Apr 20, 20268 min read

Case StudySystem Design Interview Mastery

#ai-ml#aws#system-design

System DesignAdvanced

System Design: Designing a Global Payment Gateway (Stripe Scale)

System Design Masterclass: Designing a Payment Gateway (Stripe) Mental Model > Connecting isolated components into a resilient, scalable, and observable distributed web. Designing a system to serve photos or short URLs i…

Apr 20, 20267 min read

Case StudyBackend Systems Mastery

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System DesignAdvanced

Project Case Study: Designing Stripe’s Ledger System

Recording transactions between millions of accounts is not a matter of simple arithmetic. It requires a system that is 100% auditable, ACID-compliant, and perfectly consistent. 1. Requirements Functional: - Immutable Aud…

Apr 20, 20268 min read

Case StudySystem Design Interview Mastery

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System DesignAdvanced

System Design: Designing Twitter (Timeline and News Feed)

Twitter (now X) is a massive real-time messaging system. The core technical challenge is not storing the tweets, but delivering them to millions of followers' timelines with sub-second latency. 1. Core Requirements - Twe…

Apr 20, 20268 min read

Case StudySystem Design Interview Mastery

#databases#system-design

System DesignAdvanced

Designing a High-Throughput Notification System for 100K Events per Second

100,000 events per second is not a notification system problem — it's a data pipeline problem that happens to produce notifications. Teams that approach it as a features problem ("we just need push, email, and SMS") buil…

May 10, 202511 min read

Case StudySystem Design Interview Mastery

#messaging#performance#system-design

DatabasesAdvanced

Designing a Database Sharding Strategy for 100 Million Users

Vertical scaling has a ceiling. For most applications, that ceiling arrives somewhere between 1 million and 10 million users, depending on write patterns and data size. At 100 million users, the question is not whether t…

Apr 14, 202511 min read

Case StudyBackend Systems Mastery

#databases#system-design