#OOP — ByteDepth

Low Level Design

Design a Conference Room Booking System

Low-level design of a thread-safe office room booking system featuring Singleton, Facade, Strategy (pluggable room selection), Observer (Email/Calendar/Slack notifications), Builder for recurring bookings, and atomic rollback.

Hard·Aug 21, 2026·20 min read

Low Level Design OOP Design Patterns

Low Level Design

Design Splitwise

Low-level design of an expense-sharing app — user and group management, three split strategies (equal, percentage, exact), Factory pattern for entity creation, Singleton orchestration, and a Facade that hides all internal complexity.

Hard·Aug 21, 2026·18 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Library Management System

A full low-level design for a library — rack-based book storage, dual borrow flows (by book ID or copy ID), multi-attribute search, borrow-log tracking, and a thin facade that separates the public API from the core engine.

Medium·Aug 16, 2026·18 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Notification Service

A multi-channel notification broker with per-service subscription control, parallel fan-out via an ExecutorService, exponential-backoff retry, and a Dead Letter Queue — built around Template Method, Strategy, Builder, and Singleton.

Medium·Aug 16, 2026·16 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Pub-Sub Model

Build a Publisher-Subscriber messaging system from scratch — decoupled components, dynamic topic management, and thread-safe broadcast using the Observer pattern and Singleton registry.

Medium·Aug 16, 2026·12 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Tic-Tac-Toe Game

A clean OOP design for the classic two-player grid game — pluggable winning strategies, a Singleton game controller, interface-driven board and game contracts, and a turn-based loop in Java.

Medium·Aug 16, 2026·14 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Logging Framework

A complete low-level design walkthrough for a custom logging framework — from requirements clarification to Singleton, Strategy, and Builder patterns, with async log processing and pluggable appenders in Java.

Easy·Aug 13, 2026·15 min read

Low Level Design OOP Design Patterns

Low Level Design

Design an LRU Cache

Build a fixed-capacity cache with O(1) get and put using a HashMap and a doubly linked list, with a pluggable eviction engine that cleanly separates storage from access-order tracking.

Medium·Aug 13, 2026·12 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Task Management System

A complete low-level design walkthrough for a task management system — from requirements to State, Strategy, Builder, and Singleton patterns with thread-safe task lifecycle management in Java.

Easy·Aug 13, 2026·15 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Traffic Signal Controller

A complete low-level design walkthrough for a traffic signal control system — State pattern for signal transitions, Singleton context as the FSM, and sensor-driven adaptive durations with emergency override.

Easy·Aug 11, 2026·12 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Bank Account System

A complete low-level design walkthrough for a bank account system — from requirements clarification to SOLID principles, design patterns, and a clean Java implementation with Singleton service, abstract accounts, and transaction history.

Easy·Aug 11, 2026·15 min read

Low Level Design OOP Design Patterns

Low Level Design

Design a Coffee Vending Machine

A complete low-level design walkthrough for a coffee vending machine — Singleton services, Factory for coffee types, synchronized thread safety, and inventory tracking with low-stock alerts.

Easy·Aug 11, 2026·15 min read

Low Level Design OOP Design Patterns

Low Level Design

UML Class Diagrams: The Ultimate Guide

A concise guide to the core relationships in UML Class Diagrams: Association, Aggregation, Composition, Inheritance, Realization, and Dependency, with clear definitions and real-world examples.

Dec 18, 2025

Low Level Design UML Class Diagrams

Low Level Design

Building a Scalable Weather Station

A Practical Look at Pub/Sub Architecture in Java

Easy·Nov 26, 2025

Low Level Design OOP Design Patterns

Low Level Design

How to Build a Scalable Music Service

Explore the system design of a music streaming service like Spotify. Learn about positional indexing for playlists, handling concurrency with the Actor model, low-latency playback architecture, and the design patterns that make it scale to millions of users.

Hard·Nov 24, 2025

Low Level Design OOP Design Patterns

Low Level Design

Design a Parking Lot

A complete low-level design walkthrough for a multi-level parking lot system — from requirements clarification to class diagrams, design patterns, and thread-safe Java implementation.

Easy·Aug 10, 2025·18 min read

Low Level Design OOP Design Patterns

Low Level Design

Deep Dive into Low Level Design (LLD)

Dive into the world of Low-Level Design (LLD) with this comprehensive guide. Whether you're prepping for interviews or strengthening your system design skills, this blog covers it all — essential topics, must-practice questions, core design patterns explained with real-world analogies, and annotated sample code snippets. Perfect for developers aiming to write clean, scalable, and maintainable code.

Jul 15, 2025

Low Level Design OOP SOLID