53 articles in low level design › real-world lld.
OOP design for a two-player chess game covering piece hierarchy via inheritance, move validation via polymorphism, check/checkmate detection, and game state coordination.
OOP design for a library system covering book catalog management, member lending with borrow limits, fine calculation, and search functionality.
OOP design for a banking system covering account types, transaction processing, overdraft protection, and thread-safe balance operations.
State machine design for a vending machine covering State pattern, coin handling, product dispensing, change calculation, and inventory management.
State machine design for an ATM covering card authentication, transaction types (withdraw, deposit, balance check), cash dispensing, and account interaction.
OOP design for a hotel booking system covering room inventory, reservation management, date-range conflict detection, pricing strategies, and cancellation policies.
Low-level design of a social-media post system -- creating posts with text/images/video, reactions (like/love/haha), threaded comments, feed generation, visibility controls, and content moderation hooks.
OOP design for movie ticket booking covering show scheduling, seat selection with locking, payment processing, and concurrent booking handling.
Low-level design for a Jira-style task tracker -- projects, boards, task lifecycle (To Do -> In Progress -> Done), assignment, priority, sprint management, and filtering/search.
OOP design for an e-commerce shopping cart covering price snapshots, coupon application via Strategy pattern, inventory checks, and cart merging on login.
LLD of an airline reservation system covering flight inventory, cabin classes, overbooking strategy, fare rules, booking with payment, and involuntary denied boarding handling.
Low-level design of an online auction system covering item listing, bid placement, auction lifecycle, anti-sniping extensions, proxy/auto-bidding, winner determination, and real-time bid notifications.
Low-level design for a food-delivery platform: restaurant menu management, cart and order processing, delivery assignment, order state machine, pricing with promotions, and real-time tracking notifications.
Low-level design of a multi-channel notification system -- email, SMS, push, and in-app channels with user preferences, template rendering, retry on failure, rate limiting per user, and a priority queue for urgent notifications.
Low-level design of a plugin system -- plugin interface contract, lifecycle management (load/start/stop/unload), dependency resolution, hook points, sandboxed execution, and version compatibility.
Low-level design of an in-process rate limiter -- token bucket, sliding window, and leaky bucket algorithms. Covers per-key limits, burst handling, thread-safe token management, and composable multi-tier limiting.
Low-level design of a configurable retry library -- retry policies (fixed, exponential backoff, jitter), retryable vs non-retryable exceptions, max attempts, timeout budget, and circuit-breaker integration.
Low-level design of a thread-safe database connection pool. Covers min/max pool size, acquire timeout, connection health checks, connection lifecycle (create/validate/evict), and metrics for monitoring pool exhaustion.
Low-level design of a publish-subscribe event bus -- topic registration, subscriber management, synchronous vs asynchronous dispatch, wildcard routing, dead-letter handling, and thread safety.
Low-level design for a feature-flag evaluation engine -- boolean and percentage rollouts, user targeting rules, flag dependencies, override precedence, and audit logging. Covers Strategy for evaluation, Composite for rule trees, and Observer for flag-change propagation.
Low-level design of an in-memory key-value cache. Covers eviction policies (LRU, LFU, TTL), thread-safe concurrent access, capacity management, and cache statistics for hit-rate monitoring.
Low-level design of an in-process job scheduler -- one-shot and recurring jobs, cron expressions, priority queue scheduling, thread-pool execution, retry with backoff, job state machine, and graceful shutdown.
Low-level design of a pluggable logging framework -- log levels, appender pipeline, formatter strategy, logger hierarchy, async buffered writes, and structured JSON output.
OOP design for a tic-tac-toe game covering board management, turn validation, win detection with O(1) checking, and extensible grid sizes.
OOP design for a snake-and-ladder game covering board setup with configurable snakes and ladders, dice rolling, player movement with overlap handling, and win detection.
OOP design for minesweeper covering grid generation with mine placement, recursive cell revealing with BFS/DFS flood fill, flagging, adjacency counting, and game state management.
OOP design for a multi-level parking lot covering vehicle types, spot allocation strategies, ticket management, payment processing, and capacity tracking with thread-safe operations.
OOP design for a multi-elevator system covering scheduling algorithms (SCAN, LOOK, nearest-car), request queuing, direction management, door state machines, and capacity handling.
OOP design for a traffic signal control system covering intersection modeling, signal state machines, phase scheduling, emergency vehicle preemption, and adaptive timing.
OOP design for a coffee vending machine covering State pattern for machine lifecycle, beverage recipes with ingredient management, payment processing, and inventory tracking.
OOP design for an expense-splitting application covering group management, multiple split strategies (equal, exact, percentage), balance simplification with debt graph minimization, and settlement tracking.
OOP design for a ride-sharing platform covering rider-driver matching, trip lifecycle management, fare estimation with surge pricing, location tracking with spatial indexing, and rating systems.
OOP design for a meeting scheduler covering calendar management, conflict detection with interval overlap checking, room booking, recurring meetings, and participant availability finding.
OOP design for a car rental platform covering vehicle inventory management, reservation lifecycle, pricing strategies, branch/location management, and late return penalty handling.
OOP design for an e-commerce platform covering product catalog, shopping cart, order lifecycle, inventory management, payment processing, and seller marketplace with search and filtering.
OOP design for a package locker system covering locker size allocation, OTP-based access, package lifecycle tracking, expiry handling, and multi-location management.
OOP design for a real-time chat application covering user management, direct and group messaging, message delivery states, online presence tracking, and chat history with read receipts.
OOP design for a payment gateway covering transaction lifecycle, multi-provider routing with Strategy pattern, idempotency handling, retry logic, refund processing, and fraud detection hooks.
OOP design for a stock exchange covering order matching engine with price-time priority, order book management, limit and market orders, trade execution, and portfolio tracking.
OOP design for a professional networking platform covering user profiles, connections, job postings, feed generation, endorsements, and messaging.
OOP design for a Q&A platform covering question and answer posting, voting system, reputation tracking, tag-based search, comment threads, and answer acceptance with privilege escalation.
OOP design for a social network covering user profiles, friend connections with graph modeling, news feed generation, post creation with privacy controls, and notification systems.
OOP design for a music streaming platform covering songs, playlists, albums, artist profiles, playback queue, shuffle algorithms, and subscription tiers.
OOP design for an inventory management system covering product catalog, stock tracking, warehouse management, reorder alerts, and batch operations with audit trails.
OOP design for an online learning platform covering course catalog, enrollment management, lesson sequencing, progress tracking, quiz engine, and certificate generation.
OOP design for a live cricket scoring platform covering match management, innings and over tracking, ball-by-ball scoring, player statistics, scoreboard computation, and live commentary.
OOP design for a restaurant management system covering table reservations, menu management, order processing, kitchen workflow, billing with split payments, and staff coordination.
OOP design for a probabilistic data structure that tests set membership with no false negatives. Covers hash function selection, optimal bit array sizing, false positive rate tuning, and counting bloom filters.
OOP design for a type-ahead search suggestion system using a Trie data structure. Covers prefix matching, ranking by frequency, top-K results, and real-time suggestion updates.
OOP design for an in-memory search engine covering document indexing, inverted index construction, TF-IDF ranking, boolean queries (AND/OR/NOT), and result pagination.
OOP design for a URL shortening service covering short code generation, base62 encoding, collision handling, expiration policies, click analytics, and rate limiting.
OOP design for an in-memory file system covering files and directories as a tree, path resolution, CRUD operations, search by name/extension, and permission management.
OOP design for a Git-like version control system covering repositories, commits as a DAG, branching, merging, diffs, staging area, and conflict detection.