{"id":55249,"url":"https://github.com/ashishps1/awesome-low-level-design","name":"awesome-low-level-design","description":"Learn Low Level Design (LLD) and prepare for interviews using free resources.","projects_count":69,"last_synced_at":"2026-09-29T20:00:25.266Z","repository":{"id":212990876,"uuid":"719980575","full_name":"ashishps1/awesome-low-level-design","owner":"ashishps1","description":"Learn Low Level Design (LLD) and prepare for interviews using free resources.","archived":false,"fork":false,"pushed_at":"2026-08-19T08:47:42.000Z","size":15979,"stargazers_count":26689,"open_issues_count":81,"forks_count":6475,"subscribers_count":169,"default_branch":"main","last_synced_at":"2026-09-09T22:06:57.565Z","etag":null,"topics":["awesome","design-patterns","interview","interview-practice","interview-questions","lld","low-level-design","machine-coding","object-oriented-programming","oops","solid-principles","uml"],"latest_commit_sha":null,"homepage":"https://algomaster.io","language":"Java","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"gpl-3.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/ashishps1.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null,"zenodo":null,"notice":null,"maintainers":null,"copyright":null,"agents":null,"claude":null,"gemini":null,"cursor":null,"copilot":null,"dco":null,"cla":null,"disclosure":null}},"created_at":"2023-11-17T10:15:12.000Z","updated_at":"2026-09-09T21:00:27.000Z","dependencies_parsed_at":"2026-09-09T22:11:01.932Z","dependency_job_id":null,"html_url":"https://github.com/ashishps1/awesome-low-level-design","commit_stats":null,"previous_names":["ashishps1/awesome-low-low-design"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/ashishps1/awesome-low-level-design","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ashishps1%2Fawesome-low-level-design","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ashishps1%2Fawesome-low-level-design/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ashishps1%2Fawesome-low-level-design/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ashishps1%2Fawesome-low-level-design/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/ashishps1","download_url":"https://codeload.github.com/ashishps1/awesome-low-level-design/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ashishps1%2Fawesome-low-level-design/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":342085742,"owners_count":37856553,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-08-22T15:14:58.755Z","status":"online","status_checked_at":"2026-09-29T02:00:06.972Z","response_time":187,"last_error":null,"robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"created_at":"2024-01-24T14:46:26.139Z","updated_at":"2026-09-29T20:00:25.267Z","primary_language":null,"list_of_lists":false,"displayable":true,"categories":["Additional resources","Design Patterns","Fundamental Concepts","⚙️ Design Patterns","🧭 Design Principles","UML","Low Level Design Interview Problems","📚 Books","Additional Resources","📌 Fundamental Concepts","🗂️ UML","📇 Courses","📩 Newsletter","🧩 Design Patterns","🧱 OOP Fundamentals","🔗 Class Relationships","⏱️ Concurrency and Multi-threading Concepts","⏱️ Concurrency and Multi-threading Problems","🏁 Start Here"],"sub_categories":["Hard Problems","Creational Patterns","Structural Patterns","Behavioral Patterns","Easy","Hard","Concurrency 101","Synchronization Primitives","Concurrency Challenges","Concurrency Patterns"],"readme":"\u003cp align=\"center\"\u003e\n  \u003cimg src=\"images/lld-repo-logo.png\" width=\"350\" height=\"200\"\u003e\n\u003c/p\u003e\n\u003cp align=\"center\"\u003e\n  \u003ca href=\"https://blog.algomaster.io/\"\u003eJoin Free Newsletter\u003c/a\u003e\n\u003c/p\u003e\n\nThis repository contains resources to learn Low Level Design (LLD) / Object Oriented Design (OOD) and prepare for interviews. It covers OOP fundamentals, design patterns, UML, concurrency and commonly asked interview questions.\n\n## 🏁 Start Here\n- [How to Learn LLD](https://algomaster.io/learn/lld/how-to-learn-lld)\n- [15 Must-Know OOP Concepts](https://algomaster.io/learn/lld/15-must-know-oop-concepts)\n\n## 🧱 OOP Fundamentals\n- [Classes and Objects](https://algomaster.io/learn/lld/classes-and-objects)\n- [Enums](https://algomaster.io/learn/lld/enums)\n- [Interfaces](https://algomaster.io/learn/lld/interfaces)\n- [Encapsulation](https://algomaster.io/learn/lld/encapsulation)\n- [Abstraction](https://algomaster.io/learn/lld/abstraction)\n- [Inheritance](https://algomaster.io/learn/lld/inheritance)\n- [Polymorphism](https://algomaster.io/learn/lld/polymorphism)\n\n## 🔗 Class Relationships\n- [Association](https://algomaster.io/learn/lld/association)\n- [Aggregation](https://algomaster.io/learn/lld/aggregation)\n- [Composition](https://algomaster.io/learn/lld/composition)\n- [Dependency](https://algomaster.io/learn/lld/dependency)\n\n## 🧭 Design Principles\n- [DRY Principle](https://algomaster.io/learn/lld/dry)\n- [YAGNI Principle](https://algomaster.io/learn/lld/yagni)\n- [KISS Principle](https://algomaster.io/learn/lld/kiss)\n- [SOLID Principles with Pictures](https://medium.com/backticks-tildes/the-s-o-l-i-d-principles-in-pictures-b34ce2f1e898)\n- [SOLID Principles with Code](https://blog.algomaster.io/p/solid-principles-explained-with-code)\n\n## 🧩 Design Patterns\n\n| **Creational Patterns**                                                       | **Structural Patterns**                                         | **Behavioral Patterns**                                                               |\n| ----------------------------------------------------------------------------- | --------------------------------------------------------------- | ------------------------------------------------------------------------------------- |\n| [Singleton](https://algomaster.io/learn/lld/singleton)            | [Adapter](https://algomaster.io/learn/lld/adapter)     | [Iterator](https://algomaster.io/learn/lld/iterator)                         |\n| [Factory Method](https://algomaster.io/learn/lld/factory-method)     | [Bridge](https://algomaster.io/learn/lld/bridge)       | [Observer](https://algomaster.io/learn/lld/observer)                         |\n| [Abstract Factory](https://algomaster.io/learn/lld/abstract-factory) | [Composite](https://algomaster.io/learn/lld/composite) | [Strategy](https://algomaster.io/learn/lld/strategy)                         |\n| [Builder](https://algomaster.io/learn/lld/builder)                   | [Decorator](https://algomaster.io/learn/lld/decorator) | [Command](https://algomaster.io/learn/lld/command)                           |\n| [Prototype](https://algomaster.io/learn/lld/prototype)               | [Facade](https://algomaster.io/learn/lld/facade)       | [State](https://algomaster.io/learn/lld/state)                               |\n|                                                                               | [Flyweight](https://algomaster.io/learn/lld/flyweight) | [Template Method](https://algomaster.io/learn/lld/template-method)           |\n|                                                                               | [Proxy](https://algomaster.io/learn/lld/proxy)         | [Visitor](https://algomaster.io/learn/lld/visitor)                           |\n|                                                                               |                                                                 | [Mediator](https://algomaster.io/learn/lld/mediator)                         |\n|                                                                               |                                                                 | [Memento](https://algomaster.io/learn/lld/memento)                           |\n|                                                                               |                                                                 | [Chain of Responsibility](https://algomaster.io/learn/lld/chain-of-responsibility) |\n\n## 🗂️ UML\n- [Class Diagram](https://algomaster.io/learn/lld/class-diagram)\n- [Use Case Diagram](https://algomaster.io/learn/lld/use-case-diagram)\n- [Sequence Diagram](https://algomaster.io/learn/lld/sequence-diagram)\n- [Activity Diagram](https://algomaster.io/learn/lld/activity-diagram)\n- [State Machine Diagram](https://algomaster.io/learn/lld/state-machine-diagram)\n\n## ⏱️ Concurrency and Multi-threading Concepts\n### Concurrency 101\n- [Introduction to Concurrency](https://algomaster.io/learn/concurrency-interview/introduction-to-concurrency)\n- [Concurrency vs Parallelism](https://algomaster.io/learn/concurrency-interview/concurrency-vs-parallelism)\n- [Processes vs Threads](https://algomaster.io/learn/concurrency-interview/processes-vs-threads)\n- [Thread Lifecycle and States](https://algomaster.io/learn/concurrency-interview/thread-lifecycle-and-states)\n- [Race Conditions and Critical Sections](https://algomaster.io/learn/concurrency-interview/race-conditions-and-critical-sections)\n### Synchronization Primitives\n- [Mutex (Mutual Exclusion)](https://algomaster.io/learn/concurrency-interview/mutex)\n- [Semaphores](https://algomaster.io/learn/concurrency-interview/semaphores)\n- [Condition Variables](https://algomaster.io/learn/concurrency-interview/condition-variables)\n- [Coarse-grained vs Fine-grained Locking](https://algomaster.io/learn/concurrency-interview/coarse-vs-fine-grained-locking)\n- [Reentrant Locks](https://algomaster.io/learn/concurrency-interview/reentrant-locks)\n- [Try-Lock and Timed Locking](https://algomaster.io/learn/concurrency-interview/try-lock-and-timed-locking)\n- [Compare-and-Swap (CAS)](https://algomaster.io/learn/concurrency-interview/compare-and-swap)\n### Concurrency Challenges\n- [Deadlock](https://algomaster.io/learn/concurrency-interview/deadlock)\n- [Livelock](https://algomaster.io/learn/concurrency-interview/livelock)\n### Concurrency Patterns\n- [Signaling Pattern](https://algomaster.io/learn/concurrency-interview/signaling-pattern)\n- [Thread Pool Pattern](https://algomaster.io/learn/concurrency-interview/thread-pool-pattern)\n- [Producer-Consumer Pattern](https://algomaster.io/learn/concurrency-interview/producer-consumer-pattern)\n- [Reader-Writer Pattern](https://algomaster.io/learn/concurrency-interview/reader-writer-pattern)\n\n## ✅ [How to Answer a LLD Interview Problem](https://blog.algomaster.io/p/how-to-answer-a-lld-interview-problem)\n\u003cimg src=\"images/interview-template.png\" width=\"350\" height=\"250\"\u003e\n\n## 💻 Low Level Design Interview Problems\n### Easy Problems\n\n- [Design Parking Lot](problems/parking-lot.md)\n- [Design Stack Overflow](problems/stack-overflow.md)\n- [Design a Vending Machine](problems/vending-machine.md)\n- [Design Logging Framework](problems/logging-framework.md)\n- [Design Traffic Signal Control System](problems/traffic-signal.md)\n- [Design Coffee Vending Machine](problems/coffee-vending-machine.md)\n- [Design a Task Management System](problems/task-management-system.md)\n\n### Medium Problems\n\n- [Design ATM](problems/atm.md)\n- [Design LinkedIn](problems/linkedin.md)\n- [Design LRU Cache](problems/lru-cache.md)\n- [Design Tic Tac Toe Game](problems/tic-tac-toe.md)\n- [Design Pub Sub System](problems/pub-sub-system.md)\n- [Design an Elevator System](problems/elevator-system.md)\n- [Design Car Rental System](problems/car-rental-system.md)\n- [Design an Online Auction System](problems/online-auction-system.md)\n- [Design Hotel Management System](problems/hotel-management-system.md)\n- [Design a Digital Wallet Service](problems/digital-wallet-service.md)\n- [Design Airline Management System](problems/airline-management-system.md)\n- [Design a Library Management System](problems/library-management-system.md)\n- [Design a Social Network like Facebook](problems/social-networking-service.md)\n- [Design Restaurant Management System](problems/restaurant-management-system.md)\n- [Design a Concert Ticket Booking System](problems/concert-ticket-booking-system.md)\n\n### Hard Problems\n\n- [Design CricInfo](problems/cricinfo.md)\n- [Design Splitwise](problems/splitwise.md)\n- [Design Chess Game](problems/chess-game.md)\n- [Design a Snake and Ladder game](problems/snake-and-ladder.md)\n- [Design Ride-Sharing Service like Uber](problems/ride-sharing-service.md)\n- [Design Course Registration System](problems/course-registration-system.md)\n- [Design Movie Ticket Booking System](problems/movie-ticket-booking-system.md)\n- [Design Online Shopping System like Amazon](problems/online-shopping-service.md)\n- [Design Online Stock Brokerage System](problems/online-stock-brokerage-system.md)\n- [Design Music Streaming Service like Spotify](problems/music-streaming-service.md)\n- [Design Online Food Delivery Service like Swiggy](problems/food-delivery-service.md)\n\n## ⏱️ Concurrency and Multi-threading Problems\n\n- [Print FooBar Alternately](https://algomaster.io/learn/concurrency-interview/print-foobar-alternately)\n- [Print Zero Even Odd](https://algomaster.io/learn/concurrency-interview/print-zero-even-odd)\n- [Fizz Buzz Multithreaded](https://algomaster.io/learn/concurrency-interview/fizz-buzz-multithreaded)\n- [Building H2O Molecule](https://algomaster.io/learn/concurrency-interview/building-h2o)\n- [Design Thread-Safe Cache with TTL](https://algomaster.io/learn/concurrency-interview/design-thread-safe-cache-with-ttl)\n- [Design Concurrent HashMap](https://algomaster.io/learn/concurrency-interview/design-concurrent-hashmap)\n- [Design Thread-Safe Blocking Queue](https://algomaster.io/learn/concurrency-interview/design-thread-safe-blocking-queue)\n- [Design Concurrent Bloom Filter](https://algomaster.io/learn/concurrency-interview/design-concurrent-bloom-filter)\n- [Multi-threaded Merge Sort](https://algomaster.io/learn/concurrency-interview/multi-threaded-merge-sort)\n\n## 📇 Courses\n- [Master LLD Interviews - AlgoMaster.io](https://algomaster.io/learn/lld/course-introduction)\n- [Master Concurrency Interviews - AlgoMaster.io](https://algomaster.io/learn/concurrency-interview)\n\n## 📚 Books\n- [Head First Design Patterns](https://www.amazon.in/dp/9385889753)\n- [Clean Code](https://www.amazon.in/dp/B001GSTOAM)\n- [Refactoring: Improving the Design of Existing Code](https://www.amazon.in/dp/0134757599)\n\n## 📩 Newsletter\n- [AlgoMaster Newsletter](https://blog.algomaster.io/)\n\n## Additional resources\n- [Coursera - Object-Oriented Design](https://www.coursera.org/learn/object-oriented-design)\n- [Coursera - Design Patterns](https://www.coursera.org/learn/design-patterns)\n- [Github - Awesome Design Patterns](https://github.com/DovAmir/awesome-design-patterns)\n\n## 🤝 Contributing\nContributions are welcome! If you'd like to add a new problem, improve existing content, or fix errors:\n1. Fork the repository\n2. Create a feature branch: `git checkout -b feature/your-feature-name`\n3. Commit your changes: `git commit -m 'Add some feature'`\n4. Push to the branch: `git push origin feature/your-feature-name`\n5. Submit a pull request\n\nPlease make sure to update Readme files and documentation as appropriate.\n\n---\n\n\u003cp align=\"center\"\u003e\n  \u003ci\u003eIf you find this resource helpful, please give it a star and share it with others!\u003c/i\u003e\n\u003c/p\u003e\n","projects_url":"https://awesome.ecosyste.ms/api/v1/lists/ashishps1%2Fawesome-low-level-design/projects"}