awesome-low-level-design: Low Level Design Interview Prep
/awesome-low-level-design
awesome-low-level-design is worth bookmarking if you're grinding LLD interviews and want one page linking to OOP basics, the standard design patterns, and dozens of practice problems instead of hunting across a dozen separate blogs. The catch: most links point to a single external site, AlgoMaster.io, so you're trusting one author's explanations rather than a curated mix of sources. Treat it as a syllabus, not a textbook.
What is awesome-low-level-design?
awesome-low-level-design is a GitHub repository, not a course or app, that organizes free links for learning Low Level Design (LLD) and object-oriented design ahead of technical interviews. It groups resources into OOP fundamentals, class relationships, SOLID and design principles, the classic design patterns, UML diagrams, and concurrency, plus a folder of LLD problems like a parking lot, an ATM, and a ride-sharing service like Uber.
What topics and problems does the collection cover?
- ✓OOP fundamentals — classes, interfaces, encapsulation, abstraction, inheritance, and polymorphism, each linked to its own explainer.
- ✓Class relationships — association, aggregation, composition, and dependency, the vocabulary interviewers expect in a design walkthrough.
- ✓Design principles: DRY, YAGNI, KISS, plus two separate write-ups of SOLID, one with pictures and one with code.
- ✓Creational, structural, and behavioral design patterns, from Singleton through Chain of Responsibility, each with its own AlgoMaster.io page.
- ✓UML diagram types — class, use case, sequence, activity, and state machine diagrams.
- ✓Concurrency and multi-threading, from processes vs threads and race conditions to mutexes, semaphores, CAS, deadlock, and producer-consumer patterns.
- ✓A tiered folder of LLD interview problems (easy, medium, hard) covering systems like a vending machine, elevator, Splitwise, and a movie ticket booking system.
- ✓A short list of add-ons: two AlgoMaster.io courses, three books (Head First Design Patterns, Clean Code, Refactoring), and a newsletter.
How to use awesome-low-level-design for interview prep
- •Read the OOP fundamentals and class relationships links first if you're rusty — the pattern problems assume you already know composition from inheritance.
- •Work through the Easy problems (parking lot, vending machine, logging framework) before touching Hard ones like CricInfo or a ride-sharing service.
- •Pair each pattern page with the matching problem — read Observer, then try designing a pub-sub system — instead of memorizing definitions in isolation.
- •Use the concurrency section on its own if your loop includes a multi-threading round; it's a separate track with its own problem set.
- •Read "How to Answer a LLD Interview Problem" before your first mock interview to learn the structure interviewers expect.
Strengths
- ✓One page covers the whole LLD interview syllabus — OOP, patterns, UML, concurrency, and problems — instead of five separate roadmap repos.
- ✓Problems are split into Easy/Medium/Hard tiers with real interview-style prompts (ATM, LRU cache, Splitwise, ride-sharing service), not generic pattern drills.
- ✓Concurrency gets its own dedicated track, including synchronization primitives and concurrency-specific problems like Print FooBar Alternately.
- ✓Free end to end: no login, no paywall, just links plus two book recommendations if you want to go deeper.
Limitations of a link-collection approach to learning LLD
- △Almost every link routes to one external site, AlgoMaster.io, run by the repo's author — you're relying on a single explainer's take, not a curated mix of sources.
- △It's a link index, not a written guide: the README itself has almost no original explanation, so it depends heavily on AlgoMaster.io staying online and unchanged.
- △Problems link to individual markdown files in a problems/ folder rather than full worked solutions with code for every entry, so depth varies by problem.
- △No stated maintenance cadence in the README, so how current the linked content stays over time isn't something this repo itself tracks.
Alternative resources for low level design preparation
Frequently asked questions about LLD interviews
LLD interviews typically cover OOP fundamentals (classes, interfaces, encapsulation, inheritance), class relationships like composition and aggregation, SOLID and other design principles, the classic design patterns, UML diagramming, and — often — concurrency and multi-threading for systems that need to be thread-safe.
awesome-low-level-design doesn't publish an exact total, but it organizes its practice problems into Easy, Medium, and Hard tiers covering systems such as a parking lot, an ATM, an elevator, Splitwise, and a ride-sharing service like Uber, plus a separate set of concurrency-specific problems.
awesome-low-level-design is free to use — it's a public GitHub repository licensed under GPL-3.0, and every linked resource in the README is free to read without a login.
awesome-low-level-design doesn't state a prep timeline, and there isn't one right answer — it depends on how many of the Easy, Medium, and Hard problems you work through and how well you already know OOP fundamentals and the patterns. Treat it as a syllabus to pace yourself against, not a fixed-length course.
awesome-low-level-design doesn't rank patterns by interview frequency, but it lists the standard creational patterns (Singleton, Factory Method, Builder), structural patterns (Adapter, Decorator, Proxy), and behavioral patterns (Observer, Strategy, State) that LLD interview problems commonly draw on.
Low level design (LLD) focuses on how individual components work internally — classes, interfaces, and their relationships, often shown as UML class or sequence diagrams. High level design (HLD) focuses on how a system's major components fit together — services, databases, caching, and scaling. awesome-low-level-design focuses specifically on the LLD half of that split.
Who should try it — and who should skip
Try this if you have a technical interview loop with a machine-coding or LLD round coming up and you want one bookmarkable index of OOP, pattern, UML, and concurrency links instead of ten separate browser tabs. Skip it if you want fully worked solutions with tests for every problem — most entries link out rather than including a self-contained write-up — or if you're prepping for HLD/system-design rounds only, since the problems/ folder is about class design, not distributed-systems trade-offs.
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