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System Design 101

Explain complex systems using visuals and simple terms.

Whether you're preparing for a System Design Interview or you simply want to understand how systems work beneath the surface, we hope this repository will help you achieve that.

Table of Contents

• API and Web Development
• Short/long polling, SSE, WebSocket
• Load Balancer Realistic Use Cases
• 5 HTTP Status Codes That Should Never Have Been Created
• How does gRPC work?
• How NAT Enabled the Internet
• Important Things About HTTP Headers
• Internet Traffic Routing Policies
• How Browsers Render Web Pages
• What makes HTTP2 faster than HTTP1?
• What is CSS (Cascading Style Sheets)?
• Key Use Cases for Load Balancers
• 18 Common Ports Worth Knowing
• What are the differences between WAN, LAN, PAN and MAN?
• How does Javascript Work?
• 8 Tips for Efficient API Design
• Reverse Proxy vs. API Gateway vs. Load Balancer
• How does REST API work?
• Load Balancer vs. API Gateway
• How GraphQL Works at LinkedIn
• GraphQL Adoption Patterns
• A cheat sheet for API designs
• API Gateway 101
• Top 3 API Gateway Use Cases
• What do version numbers mean?
• Do you know all the components of a URL?
• Unicast vs Broadcast vs Multicast vs Anycast
• 10 Essential Components of a Production Web Application
• URL, URI, URN - Differences Explained
• API vs SDK
• A Cheatsheet to Build Secure APIs
• HTTP Status Codes You Should Know
• SOAP vs REST vs GraphQL vs RPC
• A Cheatsheet on Comparing API Architectural Styles
• Top 9 HTTP Request Methods
• What is a Load Balancer?
• Proxy vs Reverse Proxy
• HTTP/1 -> HTTP/2 -> HTTP/3
• Polling vs Webhooks
• How do we Perform Pagination in API Design?
• How to Design Effective and Safe APIs
• How to Design Secure Web API Access
• What Does an API Gateway Do?
• What is gRPC?
• Top 12 Tips for API Security
• Explaining 9 Types of API Testing
• REST API vs. GraphQL
• What is GraphQL?
• REST API Cheatsheet
• The Ultimate API Learning Roadmap
• The Evolving Landscape of API Protocols in 2023
• Real World Case Studies
• 100X Postgres Scaling at Figma
• API of APIs - App Integrations
• The one-line change that reduced clone times by 99% at Pinterest
• Is Telegram Secure?
• Fixing Bugs Automatically at Meta Scale
• How Levelsfyi Scaled to Millions of Users with Google Sheets
• McDonald’s Event-Driven Architecture
• Uber Tech Stack - CI/CD
• How to Design Stack Overflow
• Twitter 1.0 Tech Stack
• How does Twitter recommend “For You” Timeline in 1.5 seconds?
• How YouTube Handles Massive Video Uploads
• How Does a Typical Push Notification System Work?
• 4 Ways Netflix Uses Caching
• Netflix Tech Stack - Databases
• 0 to 1.5 Billion Guests: Airbnb's Architectural Evolution
• How Netflix Scales Push Messaging
• Netflix's Overall Architecture
• Netflix Tech Stack - CI/CD Pipeline
• How TikTok Manages a 200K File Frontend MonoRepo
• How Netflix Really Uses Java
• Evolution of Airbnb’s Microservice Architecture
• Reddit's Core Architecture
• 10 Principles for Building Resilient Payment Systems
• What is the Journey of a Slack Message?
• Top 9 Engineering Blogs
• Uber Tech Stack
• Evolution of the Netflix API Architecture
• How Discord Stores Trillions of Messages
• Twitter Architecture 2022 vs. 2012
• Evolution of Uber's API Layer
• Netflix's Tech Stack
• AI and Machine Learning
• 5 Functions to Merge Data with Pandas
• Key Data Terms
• ChatGPT Timeline
• DeepSeek 1-Pager
• The Open Source AI Stack
• What is an AI Agent?
• Data Pipelines Overview
• How does ChatGPT work?
• Database and Storage
• Read Replica Pattern
• Pessimistic vs Optimistic Locking
• How to Upload a Large File to S3
• Types of Message Queues
• Smooth Data Migration with Avro
• The Ultimate Kafka 101 You Cannot Miss
• Database Isolation Levels
• Top 6 Data Management Patterns
• Why is Kafka Fast?
• Explaining the 4 Most Commonly Used Types of Queues
• Time Series DB (TSDB) in 20 Lines
• Differences in Event Sourcing System Design
• Erasure Coding
• Delivery Semantics
• Change Data Capture: Key to Leverage Real-time Data
• Can Kafka Lose Messages?
• Storage Systems Overview
• Explain the Top 6 Use Cases of Object Stores
• Top Eventual Consistency Patterns You Must Know
• B-Tree vs. LSM-Tree
• How to Decide Which Type of Database to Use
• Cloud Database Cheat Sheet
• Types of Memory
• Understanding Database Types
• Top 4 Data Sharding Algorithms Explained
• Top 6 Database Models
• SQL Statement Execution in Database
• What is Serverless DB?
• Why PostgreSQL is the Most Loved Database
• Top 10 Most Popular Open-Source Databases
• Is PostgreSQL Eating the Database World?
• How to Choose the Right Database
• iQIYI Database Selection Trees
• 8 Data Structures That Power Your Databases
• How to Implement Read Replica Pattern
• A Crash Course on Database Sharding
• IBM MQ -> RabbitMQ -> Kafka -> Pulsar: Message Queue Evolution
• CAP Theorem: One of the Most Misunderstood Terms
• Consistent Hashing Explained
• Types of Databases
• Key Concepts to Understand Database Sharding
• Database Locks Explained
• A Cheatsheet on Database Performance
• What does ACID mean?
• Top 5 Kafka Use Cases
• Types of Memory and Storage
• 7 Must-Know Strategies to Scale Your Database
• Technical Interviews
• How do SQL Joins Work?
• What Happens When You Type google.com Into a Browser?
• What Happens When You Type a URL Into Your Browser?
• How to Ace System Design Interviews
• Recommended Materials for Technical Interviews
• Caching & Performance
• What is ELK Stack and Why is it Popular?
• Why are Content Delivery Networks (CDN) so Popular?
• How Big Keys Impact Redis Persistence
• A Beginner's Guide to CDN
• The Ultimate Redis 101
• Cache Systems Every Developer Should Know
• Top 5 Strategies to Reduce Latency
• Top 5 Caching Strategies
• Things to Consider When Using Cache
• Cache Eviction Policies
• Memcached vs Redis
• Low Latency Stock Exchange
• Cache Miss Attack
• Top 8 Cache Eviction Strategies
• How Can Cache Systems Go Wrong?
• Top 6 Elasticsearch Use Cases
• How Does CDN Work?
• How Redis Architecture Evolved
• How Does Redis Persist Data?
• How can Redis be used?
• Why is Redis so Fast?
• How to Learn Elasticsearch
• What is CDN (Content Delivery Network)?
• Frontend Performance Optimization
• Which Latency Numbers Should You Know?
• Top Caching Strategies
• Top 9 Website Performance Metrics You Cannot Ignore
• Top 5 Common Ways to Improve API Performance
• Learn Cache
• Payment and Fintech
• E-commerce Workflow
• Digital Wallets: Banks vs. Blockchain
• What is a Stop-Loss Order and How Does it Work?
• What is Web 3.0? Why doesn't it have ads?
• SWIFT Payment Messaging System
• 4 Ways of QR Code Payment
• Handling Hotspot Accounts
• Reconciliation in Payment
• Unified Payments Interface (UPI)
• How Scan to Pay Works
• Money Movement
• Payment System
• How to Learn Payments
• The Payments Ecosystem
• Foreign Exchange Payments
• How to Avoid Double Payment
• How do Apple Pay and Google Pay work?
• How VISA Works When Swiping a Credit Card
• How ACH Payment Works
• How does Visa make money?
• Software Architecture
• Inter-Process Communication on Linux
• Orchestration vs. Choreography in Microservices
• UML Class Diagrams Cheatsheet
• Amazon Prime Video Monitoring Service
• Is Microservice Architecture the Silver Bullet?
• Database Middleware
• 9 Best Practices for Developing Microservices
• Design Patterns Cheat Sheet
• Key Terms in Domain-Driven Design
• 8 Key OOP Concepts Every Developer Should Know
• 18 Key Design Patterns Every Developer Should Know
• 10 System Design Tradeoffs You Cannot Ignore
• 9 Essential Components of a Production Microservice Application
• 9 Best Practices for Building Microservices
• 8 Key Concepts in Domain-Driven Design
• 8 Common System Design Problems and Solutions
• 6 Software Architectural Patterns You Must Know
• How To Release A Mobile App
• How Do Computer Programs Run?
• Linux Boot Process Explained
• MVC, MVP, MVVM, VIPER Patterns
• The Ultimate Software Architect Knowledge Map
• Typical Microservice Architecture
• Top 5 Software Architectural Patterns
• DevTools & Productivity
• Git Commands Cheat Sheet
• How does Git Work?
• JSON Crack: Visualize JSON Files
• Git vs GitHub
• Git Merge vs. Git Rebase
• 30 Useful AI Apps That Can Help You in 2025
• Diagram as Code
• Top 9 Causes of 100% CPU Usage
• Top 6 Tools to Turn Code into Beautiful Diagrams
• Tools for Shipping Code to Production
• Making Sense of Search Engine Optimization
• Most Used Linux Commands Map
• Linux File Permissions Illustrated
• 5 Important Components of Linux
• 15 Open-Source Projects That Changed the World
• 20 Popular Open Source Projects Started by Big Companies
• Linux File System Explained
• Life is Short, Use Dev Tools
• How Git Works
• How do Companies Ship Code to Production?
• Software Development
• Top 6 Most Commonly Used Server Types
• How does Garbage Collection work?
• A Roadmap for Full-Stack Development
• What Are the Greenest Programming Languages?
• Java Collection Hierarchy
• Running C, C++, or Rust in a Web Browser
• Top 8 C++ Use Cases
• Top 6 Multithreading Design Patterns You Must Know
• Data Transmission Between Applications
• Blocking vs Non-Blocking Queue
• Big Endian vs Little Endian
• How to Avoid Crawling Duplicate URLs at Google Scale?
• 10 Books for Software Developers
• Top 8 Standards Every Developer Should Know
• How Do C++, Java, Python Work?
• 10 Key Data Structures We Use Every Day
• A Brief History of Programming Languages
• Top 6 Load Balancing Algorithms
• The Fundamental Pillars of Object-Oriented Programming
• Top 8 Programming Paradigms
• Algorithms for System Design Interviews
• Imperative vs Functional vs Object-oriented Programming
• Explaining 9 Types of API Testing
• The 9 Algorithms That Dominate Our World
• Concurrency vs Parallelism
• Linux Boot Process Explained
• 11 Steps to Go From Junior to Senior Developer
• 10 Good Coding Principles to Improve Code Quality
• Cloud & Distributed Systems
• How AWS Lambda Works Behind the Scenes
• 8 Must-Know Scalability Strategies
• System Design Cheat Sheet
• Cloud Disaster Recovery Strategies
• Vertical vs Horizontal Partitioning
• Top 9 Architectural Patterns for Data and Communication Flow
• Top 6 Cases to Apply Idempotency
• Top 5 Trade-offs in System Designs
• How to Detect Node Failures in Distributed Systems
• Why Meta, Google, and Amazon Stop Using Leap Seconds
• The Fantastic Four of System Design
• What makes AWS Lambda so fast?
• Scaling Websites for Millions of Users
• Resiliency Patterns
• 25 Papers That Completely Transformed the Computer World
• A Crash Course on Architectural Scalability
• Must Know System Design Building Blocks
• Monorepo vs. Microrepo: Which is Best?
• How to Handle Web Request Errors
• A Cheat Sheet for Designing Fault-Tolerant Systems
• Typical AWS Network Architecture
• Unique ID Generator
• Amazon's Build System: Brazil
• Infrastructure as Code Landscape Cheatsheet
• How do we manage configurations in a system?
• How do we incorporate Event Sourcing into systems?
• The 12-Factor App
• Explaining 5 Unique ID Generators
• Retry Strategies for System Failures
• Cloud Monitoring Cheat Sheet
• Why Use a Distributed Lock?
• Top 6 Cloud Messaging Patterns
• Most Important AWS Services to Learn
• How to Transform a System to be Cloud Native
• Hidden Costs of the Cloud
• 2 Decades of Cloud Evolution
• Cloud Cost Reduction Techniques
• Top 7 Most-Used Distributed System Patterns
• Cloud Load Balancer Cheat Sheet
• AWS Services Evolution
• Azure Services Cheat Sheet
• A cheat sheet for system designs
• CAP, BASE, SOLID, KISS, What do these acronyms mean?
• System Design Blueprint: The Ultimate Guide
• How to Design for High Availability
• What is Cloud Native?
• Cloud Comparison Cheat Sheet
• Big Data Pipeline Cheatsheet for AWS, Azure, and Google Cloud
• AWS Services Cheat Sheet
• How it Works?
• How do AirTags work?
• How is Email Delivered?
• Design Gmail
• How Google/Apple Maps Blur License Plates and Faces
• Quadtree
• Build a Simple Chat Application with Redis
• Live Streaming Explained
• How to Design a System for Internationalization
• How to Design Google Docs
• Payment System
• Experiment Platform Architecture
• Design Google Maps
• Designing a Chat Application
• Design Stock Exchange
• How are Notifications Pushed to Our Phones or PCs?
• What Happens When You Upload a File to Amazon S3?
• Proximity Service
• How Do Search Engines Work?
• DevOps and CI/CD
• Top 10 Kubernetes Design Patterns
• Some DevOps Books I Find Enlightening
• Paradigm Shift: Developer to Tester Ratio
• Push vs Pull in Metrics Collection Systems
• Choose the Right Database for Metric Collection
• Top 4 Kubernetes Service Types
• Cloud Native Anti-Patterns
• Kubernetes Tools Stack Wheel
• Kubernetes Tools Ecosystem
• Kubernetes Periodic Table
• 9 Docker Best Practices You Must Know
• Netflix Tech Stack - CI/CD Pipeline
• Top 8 Must-Know Docker Concepts
• CI/CD Simplified Visual Guide
• Top 5 Most-Used Deployment Strategies
• Kubernetes Command Cheatsheet
• Kubernetes Deployment Strategies
• How does Terraform turn Code into Cloud?
• DevOps vs. SRE vs. Platform Engineering
• Deployment Strategies
• Logging, Tracing, and Metrics
• Log Parsing Cheat Sheet
• DevOps vs NoOps: What's the Difference?
• Why is Nginx so Popular?
• What is Kubernetes (k8s)?
• How does Docker work?
• CI/CD Pipeline Explained in Simple Terms
• Security
• What is DevSecOps?
• Encoding vs Encryption vs Tokenization
• Storing Passwords Safely: A Comprehensive Guide
• Designing a Permission System
• How Password Managers Work
• Is PassKey Shaping a Passwordless Future?
• Firewall Explained to Kids and Adults
• Cookies vs Sessions
• HTTP Cookies Explained With a Simple Diagram
• Token, Cookie, Session
• Sessions, Tokens, JWT, SSO, and OAuth Explained
• How to Design a Secure System
• Top 6 Firewall Use Cases
• Top 4 Authentication Mechanisms
• How Digital Signatures Work
• How do we manage sensitive data in a system?
• HTTPS, SSL Handshake, and Data Encryption Explained
• Symmetric vs Asymmetric Encryption
• Session-based Authentication vs. JWT
• JWT 101: Key to Stateless Authentication
• Is HTTPS Safe?
• Cybersecurity 101
• Cookies vs Sessions vs JWT vs PASETO
• How does SSH work?
• How Does a VPN Work?
• How Google Authenticator Works
• Types of VPNs
• What is a Cookie?
• OAuth 2.0 Flows
• Top Network Security Cheatsheet
• What is SSO (Single Sign-On)?
• How does HTTPS work?
• Session, Cookie, JWT, Token, SSO, and OAuth 2.0 Explained
• Explaining JSON Web Token (JWT) to a 10 Year Old Kid
• OAuth 2.0 Explained With Simple Terms
• Computer Fundamentals
• Paging vs Segmentation
• IPv4 vs. IPv6: Differences
• Top 4 Most Popular Use Cases for UDP
• How Does the Domain Name System (DNS) Lookup Work?
• DNS Record Types You Should Know
• TCP vs UDP for Online Gaming
• What is a Deadlock?
• Process vs Thread: Key Differences
• OSI Model Explained
• Visualizing a SQL Query
• Explaining 8 Popular Network Protocols in 1 Diagram
• What is the Best Way to Learn SQL?

License

This work is licensed under CC BY-NC-ND 4.0