Low & High Level System Design
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Low Level System Design
Low Level Design Basic Building Blocks
Learn core LLD concepts like inheritance, association, composition, aggregation, with a quick quiz to test understanding.
SOLID Principles
Understand SOLID principles to design clean, scalable, and maintainable systems, with a quiz to reinforce concepts.
Creational Design Patterns
Learn object creation patterns like Factory, Builder, Singleton, and more, with a quiz to test understanding.
Structural Design Patterns
Learn patterns like Adapter, Decorator, Facade, and Bridge to structure flexible systems, with a quiz to test understanding.
Behavioural Design Patterns
Understand interaction-focused patterns like Command, Observer, State, and Strategy, with a quiz to test concepts.
LLD Topics
Pizza factory
Design a Pizza Factory system from requirements to diagrams, code implementation, and interview Q&A.
SQL Query builder
Design an SQL Query Builder from requirements to diagrams, code implementation, and interview Q&A.
Logger
Design a Logger system covering requirements, diagrams, code, and interview Q&A
Car Price Calculator
Design a Car Price Calculator from requirements to diagrams, code implementation, and interview Q&A.
Weather Station
Design a Weather Station system from requirements to diagrams, code implementation, and interview Q&A.
Ticket management system
Design a Ticket Management System from requirements to diagrams, code implementation, and interview Q&A.
Payment processor
Design a Payment Processor from requirements to diagrams, code implementation, and interview Q&A.
Elevator System
Design an Elevator System from requirements to diagrams, code implementation, and interview Q&A.
Car parking
Design a Car Parking system covering requirements, diagrams, services, logging, design patterns, and complete code implementation.
Introduction Video
Video - 00:00:55 mins
Use Case Diagram
Video - 00:3:44 mins
Class Diagram
Video - 00:6:07 mins
Class Diagram continued
Video - 00:5:30 mins
Services
Video - 00:9:57 mins
Parking Service
Video - 00:7:59 mins
Discussion on Parking Spots and Parking Service
Video - 00:8:13 mins
Activity Diagram
Video - 00:4:17 mins
Coding Part 1
Video - 00:34:45 mins
How to add Logging in the system
Video - 00:2:20 mins
Coding Part 2 (Adding Logging in the system)
Video - 00:6:03 mins
Implementing Parking pots using Decorator Design pattern
Video - 00:2:35 mins
Coding Part 3
Video - 00:12:12 mins
Requirements
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Identification of actors
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Use case diagram
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Class diagram
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QnA
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Activity Diagram
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Code
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Social media
Design a Social Media system from requirements to diagrams, code implementation, and interview Q&A.
WhatsApp
Design a WhatsApp-like system from requirements to diagrams, code implementation, and interview Q&A.
Amazon
Design an Amazon-like system from requirements to diagrams, code implementation, and interview Q&A.
PayPal
Design a PayPal-like payment system from requirements to diagrams, code implementation, and interview Q&A.
Assignment
Apply design patterns by implementing the Snakes and Ladders game end-to-end.
High Level System Design
High Level Design ( Building Blocks )
Learn core HLD concepts like scalability, consistency, caching, databases, real-time systems, and GenAI-enabled APIs.
What is HLD?
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Consistent Hashing
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Caching
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Load Balancing
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CAP Theorem
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Indexes
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Redundancy and Replication
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SQL vs NoSQL
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Data Partitioning
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Long Polling and WebSockets
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Retrieval Augmented Generation (RAG)
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Quorum
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Gen AI-enabled API Systems
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TinyURL
Design a TinyURL system covering requirements, capacity planning, APIs, databases, caching, scaling, and testing.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High-Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Test
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Rate Limiter
Design a Rate Limiter covering requirements, capacity planning, APIs, data storage, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Typeahead suggestion (Google queries)
Design a Typeahead system covering requirements, capacity planning, APIs, data storage, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Pastebin
Design a Pastebin-like system covering requirements, capacity planning, APIs, databases, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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DropBox
Design a Dropbox-like system covering requirements, capacity planning, APIs, storage, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Instagram
Design an Instagram-like system covering requirements, capacity planning, APIs, databases, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Messenger
Design a Messenger system covering requirements, capacity planning, APIs, databases, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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BookMyShow
Design a BookMyShow-like ticketing system covering requirements, capacity planning, APIs, databases, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Uber/Ola
Design a ride-hailing system covering requirements, capacity planning, APIs, databases, real-time matching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Newsfeed
Design a Newsfeed system covering requirements, capacity planning, APIs, databases, caching, feed generation, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Youtube/Netflix
Design a video streaming system covering requirements, capacity planning, APIs, storage, caching, scaling, and reliability.
Introduction
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Requirements & Goals of the System
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Capacity Estimations & Constraints
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System APIs
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Database design & Schema
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High Level Design
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QnA
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Purging & Db Cleanup
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Database Partitioning & Replication
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Cache & Load Balancing
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Requirements of Elevator System
An Elevator System is a complex real-time control application that operates between hardware (elevator motors, sensors, doors) and software (control logic, scheduling, UI). When designing its requirements, we must think about both functional and non-functional aspects to ensure safe, efficient, and user-friendly operation.
1. Functional Requirements
These describe what the system should do in response to different events and inputs.
- Request Handling:
The system must accept elevator requests from both inside the cabin (floor selection buttons) and from outside on each floor (up/down call buttons).
- Movement Control:
The elevator should move up or down to the requested floors in an optimized and safe manner, following scheduling logic.
- Door Operations:
Automatically open and close doors at the destination floor, ensuring safety sensors prevent closing if an obstruction is detected.
- Floor Display and Indicators:
Show the current floor, direction of movement, and elevator status on digital display panels both inside and outside the elevator.
- Alarm and Emergency Button:
Allow passengers to trigger an alarm in emergencies; the system must respond by alerting building security or emergency services.
2. Non-Functional Requirements
These define how the system performs its functions, focusing on performance, reliability, and usability.
- Response Time:
The elevator should process button requests and respond within 1–2 seconds for better user experience.
- Safety and Compliance:
The elevator must comply with building safety standards, including overload prevention, fire protocols, and emergency stop.
- Availability and Uptime:
The system must be available and operational 99.9% of the time, with minimal downtime for maintenance or failure.
- Scalability:
The system should support multiple elevators working in coordination (e.g., in a high-rise building with 4–6 elevators).
- Energy Efficiency:
The movement scheduling should reduce power consumption by avoiding unnecessary travel and idle time.
3. Hardware Interaction Requirements
Because an elevator system is partly embedded software, it must interact with various hardware components:
- Sensors: Detect current floor, door state (open/closed), and overload.
- Motors: Control vertical movement of the elevator.
- User Interface Components: Buttons, displays, speaker systems, and alarms.
4. System Management Requirements
For operations and monitoring by administrators or maintenance personnel:
- Logging and Diagnostics:
Record elevator events such as movement logs, request patterns, and fault detection.
- Remote Monitoring:
Allow system administrators to view elevator status, alerts, or failures remotely.
- Manual Override Controls:
For maintenance or emergencies, staff should have the ability to operate the elevator manually.