System Design

The foundations of system design for interviews: the 7-step framework, estimation, scaling, availability, CAP, networking, load balancers, CDNs, APIs, databases, indexes, replication, and data at scale: sharding, transactions, caching and object storage.

5:40

Lesson 1

What is System Design? + The 7-Step Interview Framework

"Design Instagram." 45 minutes, a blank whiteboard. Here's exactly how to start. Lesson 1 of the complete System Design course (interview ready): what system design is, high-level vs low-level design, how a real app grows from…

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4:43

Lesson 2

Back-of-the-Envelope Estimation (Latency, QPS, Storage)

One database or fifty? You can't decide without numbers. Here's how to estimate in five minutes. Lesson 2 of the complete System Design course: back-of-the-envelope estimation.

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4:36

Lesson 3

Scalability: Vertical vs Horizontal Scaling, Stateless Servers

SnapLink needs 25,000 requests per second. One server handles 2,000. Now what? Lesson 3 of the complete System Design course: scalability.

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4:19

Lesson 4

Availability & Reliability: The Nines, SLA/SLO, Redundancy, Failover

Friday night, one disk fails, and SnapLink is down for two hours. Here's how to make sure that never happens. Lesson 4 of the complete System Design course: availability and reliability.

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4:37

Lesson 5

CAP Theorem, PACELC & Consistency Models Explained

Two ATMs, one account, one hundred rupees. Both say yes? That's the CAP theorem. Lesson 5 of the complete System Design course: CAP, PACELC and consistency models.

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4:46

Lesson 6

How the Web Works: DNS, TCP vs UDP, TLS, HTTP/2 & HTTP/3

The most famous interview question: what happens when you type a URL and press Enter? Lesson 6 of the complete System Design course: how the web works.

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4:10

Lesson 7

Load Balancers Explained: L4 vs L7, Algorithms, Health Checks

Ten servers, one address. Who decides where each request goes, and what happens when a server dies? Lesson 7 of the complete System Design course: load balancers.

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4:30

Lesson 8

CDN & Edge Caching Explained (Push vs Pull, TTL, Invalidation)

Servers in Mumbai, users in London: every photo crosses the world. Here's how CDNs fix that. Lesson 8 of the complete System Design course: CDNs and edge caching.

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4:56

Lesson 9

API Design for System Design: REST vs gRPC vs GraphQL, WebSockets, Pagination

Step three of every design interview is the API. Here's how to design one that interviewers love. Lesson 9 of the complete System Design course: API design.

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4:29

Lesson 10

SQL vs NoSQL: How to Choose a Database (4 NoSQL Types)

"NoSQL scales, SQL doesn't." Wrong, and interviewers know it. Here's how to actually choose. Lesson 10 of the complete System Design course: SQL vs NoSQL.

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4:38

Lesson 11

Database Indexes Explained: B-tree vs LSM-tree

A billion rows and one slow query. One index turns it into three page reads. Here's how. Lesson 11 of the complete System Design course: database indexes.

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4:18

Lesson 12

Database Replication Explained: Leader-Follower, Multi-Leader, Quorums

One database server means one failure takes everything down. Replication fixes that, and brings its own traps. Lesson 12 of the complete System Design course: replication.

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16:16

Lesson 13

Sharding, Transactions, Caching & Object Storage: Data at Scale Explained

4 topics in one lesson: Sharding & Consistent Hashing, Transactions & Isolation Levels, Caching Deep Dive and Object Storage & Big Files.

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More lessons are added here as they go live on YouTube.