Low-Level Design Exercises
Standard object-oriented design problems curated to help you master class structures, design patterns, and thread-safe implementations.
Select any low-level design template below to explore detailed requirements, Entity-Relationship schemas, and full multi-language code templates.
Tic Tac Toe
Design a modular, extensible Tic Tac Toe engine supporting an N x N grid, arbitrary player count, dynamic AI bot difficulty strategies, and O(1) win verification.
Traffic Signal
Design a Traffic Signal Controller managing 4-way intersections with smooth Red-Green-Yellow cycles, dynamic traffic-density durations, and emergency vehicle preemption.
Chess Clock
Design a dual-timer Chess Clock system supporting classical countdowns, Fischer and Bronstein dynamic move increments, arbiter pause controls, and flag-fall events.
Logger
Design an asynchronous logging framework with tiered severity levels (INFO, DEBUG, ERROR), a chain of responsibility handler pipeline, and pluggable sinks (Console, File, Kafka).
Coffee Machine
Design an automated Coffee Machine controller that selects recipes, verifies shared ingredient levels, manages payment transactions, and dispenses drinks with dynamic condiment decorators.
Vending Machine
Design a commercial Vending Machine controller managing inventory slots, coin insertion balance, optimal change dispensation, and transactional mechanical dispensing states.
Parking Lot System
Design a multi-story, multi-gate Parking Lot management system supporting diverse vehicle types (Motorcycle, Car, Truck, EV), dynamic spot assignment, and pluggable pricing strategies.
Snake & Ladder
Design a multiplayer Snake & Ladder board game with custom dimensions, randomized or configured snakes and ladders, flexible dice roll strategies, and cycle-free board validation.
Library Management System
Design an enterprise Library Management System managing multi-copy book lending, barcode checkouts, fine calculations, reservation queues, and pluggable catalog search algorithms.
Cricbuzz
Design a high-scale Live Cricket Commentary and Scoreboard engine broadcasting ball-by-ball events, player statistics updates, and Duckworth-Lewis-Stern target projections in real time.
Restaurant
Design a comprehensive Restaurant Management System handling table seating, digital orders, Kitchen Display System (KDS) routing, and flexible billing discount strategies.
Cache (LRU / LFU)
Design a high-performance in-memory Cache engine supporting O(1) reads and writes, configurable eviction strategies (LRU, LFU), thread safety, and transparent database proxy shielding.
File System
Design an In-Memory File System hierarchy supporting nested directories, files, path resolution, recursive disk usage calculation, and transactional commands.
Amazon Locker
Design an automated Amazon Locker network managing package dimensions, optimal locker compartment assignment, one-time secure pickup codes, and door sensor telemetry.
Online Auction System
Design an Online Auction platform managing listings, real-time bid validation, bidder price ticker notifications, auction lifecycle state transitions, and auto-sniping time extensions.
BookMyShow (Movie Ticket Booking)
Design a high-concurrency movie ticket reservation system managing multi-screen cinema seats, temporary 10-minute checkout locks, dynamic weekend pricing, and distributed locking.
Splitwise (Expense Sharing App)
Design an Expense Sharing system (like Splitwise) supporting diverse split methods (Equal, Exact, Percentage), group expense management, balance sheets, and debt simplification.
Elevator System
Design a multi-car Elevator Control System managing hall calls, car panel requests, door lifecycle states, and the LOOK/SCAN elevator scheduling dispatch algorithm.
Chess
Design a full-featured Chess game engine supporting standard 8x8 rules, piece movement strategies (Knight jump, Pawn en passant, Castling), check/checkmate detection, and command-based move history with undo/redo.
ATM Machine
Design a secure Automated Teller Machine (ATM) controller managing card insertion, PIN validation, state workflows, multi-denomination cash dispensing, and two-phase ledger commit.
Hotel Management
Design a Hotel Reservation and Management System managing multi-tier rooms (Standard, Deluxe, Suite), booking calendars, dynamic seasonal pricing, and housekeeping room turnover.
Uber
Design a high-scale Ride-Hailing Dispatch engine matching riders with nearby drivers using geospatial proximity indexing, dynamic surge multipliers, and trip state management.
Google Docs
Design a real-time Collaborative Rich-Text Document Editor supporting concurrent multi-user editing, Operational Transformation (OT) conflict resolution, and version history snapshots.
Airline Reservation
Design an Airline Reservation System managing flight instances, multi-cabin inventory tiers (Economy, Business, First), temporary seat holds, PNR booking generation, and gate update alerts.
WhatsApp / Chat System
Design a real-time Chat and Messaging service supporting direct 1:1 and group conversations, delivery receipts (Sent, Delivered, Read), media compression, and offline mailbox queues.
Inventory System
Design a Distributed Multi-Warehouse Inventory System managing SKU stock allocation, soft holds during checkout, hard deductions upon fulfillment, and automated restock orders.
Ride Sharing
Design a Carpooling / Ride-Sharing Pool engine matching multiple riders traveling in the same directional corridor, validating detour constraints, and dynamically splitting fares.