Your Archetype journey

Master Low-Level Design

Think Before You Type. Design Before You Build.

A guided, level-gated path through Low-Level Design: from OOP fundamentals to advanced machine-coding rounds.

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“Any fool can write code a computer understands. Good programmers write code humans understand.”

— Martin Fowler

The path

Level 0

OOP Foundations

The four pillars, composition vs inheritance — the vocabulary all LLD is built on.

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The Four Pillars of OOP20mComposition vs Inheritance22mAbstraction Boundaries: Interfaces, Abstract Classes, and Programming to a Contract23mClass Relationships: Association, Aggregation, Composition & Dependency24m
Level 1

Modeling & UML

Turn requirements into classes. Class & sequence diagrams, relationships, responsibilities.

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Level 2

SOLID Principles

The spine of good LLD. Spot violations, refactor toward clean, extensible designs.

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Level 3

Design Patterns

The high-frequency creational, structural, and behavioral patterns interviewers expect.

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Level 4

Core LLD Problems

Parking Lot, Vending Machine, Elevator, Splitwise — the canonical design exercises.

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Level 5

Advanced LLD

Concurrency, thread-safety, rate limiters, caches, notification systems.

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Level 6

Senior Machine Coding

Full design rounds under constraints: extensibility, trade-offs, defending decisions.

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