iiinova — where your digital self keeps evolving

Neo Kim @systemdesign.one · 08/05/2025

Here are some probabilistic data structures you must know as a software engineer (not kidding): They trade accuracy for space efficiency. They're often used in: • Databases • Cache • Search engines • Network infrastructure • Analytics What else should make this list?

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Neo Kim @systemdesign.one · 05/05/2025

If you want to reduce latency, learn these 12 rules:

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Neo Kim @systemdesign.one · 02/05/2025

Give me 2 mins and I'll teach you how DNS works:

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Neo Kim @systemdesign.one · 14/04/2025

Meta achieves 99.99999999% cache consistency. Here’s how they do it (in 2 minutes): —— 👋 PS - I put together a detailed case study with visuals in my newsletter: → newsletter.systemdesign.one/p/cache-cons...

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Neo Kim @systemdesign.one · 11/04/2025

Give me 2 mins and I'll teach you how Disney+ Hotstar scaled to 25M concurrent users—no fluff:

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Neo Kim @systemdesign.one · 10/04/2025

How I’d scale a site to 1 million users—step by step:

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Neo Kim @systemdesign.one · 07/04/2025

HTTP status codes you must know as a web developer in 2025: Status codes are 3-digit numbers returned by a server in response to HTTP requests. It tells the client about the request status and indicates problems if any. So understanding status codes will help you find site errors quickly.

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Neo Kim @systemdesign.one · 06/04/2025

This lady: • Has no tech background • Couldn't draw well as a kid • Knew nothing about venture capitalists Yet she's worth $5.8 Billion - at 37.

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Neo Kim @systemdesign.one · 02/04/2025

How to write clean code. The KYD-DTC Playbook:

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Neo Kim @systemdesign.one · 01/04/2025

Give me 2 mins and I'll teach you how a database stores passwords securely (not kidding):

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Neo Kim @systemdesign.one · 29/03/2025

Give me 2 mins and I'll teach you how Amazon S3 (actually) works:

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Neo Kim @systemdesign.one · 27/03/2025

I spent hours studying how Apple Pay works, so you don't have to. Here's what I learned distilled into 9 sentences:

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Neo Kim @systemdesign.one · 23/03/2025

Give me 2 minutes and I'll teach you how YouTube supports 2.49 billion users with MySQL (not kidding):

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Neo Kim @systemdesign.one · 22/03/2025

I spent hours studying how Amazon S3 achieves 99.999999999% durability — because S3 is the new norm. Here's what I learned distilled into 12 sentences (not kidding):

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Neo Kim @systemdesign.one · 21/03/2025

Git has 152 commands. But most people don't know the powerful ones. Here are the 4 must learn Git commands (bookmark this):

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Neo Kim @systemdesign.one · 20/03/2025

Give me 2 minutes, and I'll teach you how Uber computes ETA (not kidding):

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Neo Kim @systemdesign.one · 19/03/2025

I spent hours studying how Amazon Lambda works — because Serverless is the new norm. Here's what I learned distilled into 11 sentences (you'll thank me later):

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Neo Kim @systemdesign.one · 18/03/2025

If you want to become good at system design (I'm not joking), learn these case studies:

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Neo Kim @systemdesign.one · 17/03/2025

14 Redis use cases you must know as a software engineer (bookmark this): What else should make the list?

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Neo Kim @systemdesign.one · 16/03/2025

Bad vs Good Software Engineers What else should make this list?

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Neo Kim @systemdesign.one · 11/03/2025

Bad Debugging vs Good Debugging What else should make this list?

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Neo Kim @systemdesign.one · 28/02/2025

4 Websockets • The server keeps an open TCP connection with the client. • The server and client can communicate in real-time in both directions. What else should make this list?

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Neo Kim @systemdesign.one · 28/02/2025

3 Server-Sent Events • The server keeps an open connection with the client. • The server pushes updates to the client, but communication is unidirectional.

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Neo Kim @systemdesign.one · 28/02/2025

2 Long Polling • The server holds the client request until there's an update. • The server responds to a client only when there's an update. • The server returns an empty response on timeout.

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Neo Kim @systemdesign.one · 28/02/2025

1 Short Polling • The client periodically requests the server for an update. • The server returns an empty response if nothing has changed.

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Neo Kim @systemdesign.one · 16/02/2025

If you could only recommend 1 technical book to read, what would it be? My favorite, highly recommend

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Neo Kim @systemdesign.one · 15/02/2025

The night when I wrote my first newsletter online.

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Neo Kim @systemdesign.one · 11/02/2025

This account exists to teach you system design. I spent countless hours studying various engineering case studies. If you want to learn system design fundamentals and understand real-world software architectures, Follow me, @systemdesign.one

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Neo Kim @systemdesign.one · 09/02/2025

>Tight coupling >Longer test cycles >Slow deployments >Technology lock-in >Longer onboard time >Higher risk of failures >Single point of failures >High codebase complexity >Horizontal scalability issues What did GitHub and Stack Overflow see in Monolith?

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Neo Kim @systemdesign.one · 07/02/2025

How to crack the LEETCODE interview (without getting lucky). One of the best things you can do to become good at Leetcode is to study patterns and do mock interviews. And I created a powerful template to help you systematically approach Leetcode interviews. To get it for FREE, just:

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Neo Kim @systemdesign.one · 04/02/2025

If you want to become good at system design (I'm not kidding), learn these case studies:

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Neo Kim @systemdesign.one · 03/02/2025

Give me 2 minutes, and I'll teach you how the ride-hailing app Lyft works (I'm not kidding):

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Neo Kim @systemdesign.one · 02/02/2025

Git has 152 commands. But most people don't know the powerful commands. Here are the 4 must-know Git commands (that one day might save you):

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Neo Kim @systemdesign.one · 23/01/2025

• Imagine Bluesky has only 100 users. • The index value of people I follow is set to 1 on the Bitmap. • The people I follow are found by walking the Bitmap and recording the index of non-zero bits. • A constant time lookup tells whether I follow a specific user; but inefficient for sparse data.

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Neo Kim @systemdesign.one · 23/01/2025

• A Roaring Bitmap splits data into containers. • Each container uses a different storage mechanism based on data sparsity.

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