Series
Low-Level Design Guide
Good architecture is built on a foundation of solid low-level design. This series is a deep dive into the "micro" side of software engineering—focusing on class design, object-oriented principles (SOLID), and tactical design patterns. We explore how to translate requirements into clean, maintainable code, handle concurrency at the component level, and define clear interfaces. Whether you're preparing for LLD interviews or looking to sharpen your day-to-day coding craftsmanship, this guide provides the blueprints for building modular software.
8
Articles
3h 3m
Estimated reading
Intermediate to Advanced
Knowledge level
360
Readers
About this series
Good architecture is built on a foundation of solid low-level design. This series is a deep dive into the "micro" side of software engineering—focusing on class design, object-oriented principles (SOLID), and tactical design patterns. We explore how to translate requirements into clean, maintainable code, handle concurrency at the component level, and define clear interfaces. Whether you're preparing for LLD interviews or looking to sharpen your day-to-day coding craftsmanship, this guide provides the blueprints for building modular software.
Series Progress
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Who is this for?
Software engineers and developers learning this topic.
Knowledge Level
Intermediate to Advanced
Last Updated
May 25, 2026
Created by
Abstract Algorithms
All Articles
Article 1
LLD for Parking Lot System: Designing a Smart Garage
TLDR TLDR: A Parking Lot is the "Hello World" of Low-Level Design. It teaches Encapsulation (ParkingFloor hides its Min-Heap), Abstraction (PricingStrategy interface), Inheritance (BikeSpot/CompactSp
19 min read
Article 2
LLD for URL Shortener: Designing TinyURL
TLDR TLDR: A URL Shortener maps long URLs to short IDs. The core challenge is generating a globally unique, short, collision-free ID at scale. We use Base62 encoding on auto-incrementing database IDs
22 min read
Article 3
LLD for Movie Booking System: Designing BookMyShow
TLDR TLDR: A Movie Booking System (like BookMyShow) is an inventory management problem with an expiry: seats expire when the show starts. The core engineering challenge is preventing double-booking u
25 min read
Article 4
LLD for LRU Cache: Designing a High-Performance Cache
TLDR TLDR: An LRU (Least Recently Used) Cache evicts the item that hasn't been accessed the longest when it's full. The classic implementation combines a HashMap (O(1) lookup) with a Doubly Linked Li
25 min read
Article 5
LLD for Elevator System: Designing a Smart Lift
TLDR TLDR: An elevator system is a textbook OOP design exercise: ElevatorCar encapsulates its stop queue, ElevatorState polymorphically handles direction changes (State Pattern), and DispatchStrategy
22 min read
Article 6
Implement LLD for Parking Lot: Code Walkthrough
TLDR: This is the code companion to the Parking Lot System Design post. We implement the core classes (ParkingLot, ParkingSpot, Ticket) in Java, apply the Singleton, Factory, and Strategy patterns, an
29 min read
Article 7
LLD for Tic-Tac-Toe: Designing an Extensible OOP Game
TLDR: Tic-Tac-Toe looks trivial — until the interviewer says "make it N×N with P players and pluggable winning rules." The key design decisions: a Board abstracted from piece identity, a Strategy Patt
20 min read
Article 8
LLD for Ride Booking App: Designing Uber/Lyft
TLDR: A ride-booking system (Uber/Lyft-style) needs three interleaved sub-systems: real-time driver location tracking (Observer Pattern), nearest-driver matching (geospatial query), and dynamic pricin
21 min read
Low-Level Design Guide: Learning Roadmap
You're staring at an LLD interview question: "Design a parking lot system." You know OOP theory, but translating real-world problems into clean class hierarchies feels like a different skill entirely. The interviewer wants SOLID principles, design patterns, and interface contracts — but where do you even start?
The gap between knowing OOP concepts and applying them in interview scenarios is where most engineers stumble. This roadmap bridges that gap through a decision-tree approach: eight carefully sequenced problems that build OOP design fluency from state machines to production-grade implementations in Java Spring Boot.
TLDR: Follow the decision tree to find your learning path through 8 LLD problems, from OOP foundations to production systems, based on your timeline and interview focus.
What You'll Learn
Understand Low-Level Design Guide through real published examples
Follow a sequence of 8 articles from fundamentals to deeper topics
Connect related concepts: design patterns, Java, LLD
Practice explaining trade-offs and implementation decisions
Prerequisites
FAQs
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Start from the first article if you are new, or use the article list to jump into the most relevant topic.
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