¶00 · LLDCanvas Platform
Master LLD interviewswith real, hands-on LLD practice.
Seven features. We didn’t write another icon grid to describe them - we diagrammed them, the same way you’ll diagram your next LLD interview.
Every one links straight to its feature - click through.
¶01 · What Is Low-Level Design?
The round that grades your design, not your syntax.
Low-Level Design (LLD) - sometimes called the machine coding round or object-oriented design round - asks you to turn a real system, like a parking lot, a ride-hailing app, or a rate limiter, into classes, interfaces, and relationships that actually compile. Where a High-Level Design (HLD) interview stays at the level of services and databases, an LLD interview wants to see your UML: inheritance, composition, the design pattern you reached for, and why.
Amazon, Uber, Flipkart, Swiggy, and most product-based companies run LLD rounds specifically to see this - SOLID principles applied under time pressure, not recited from memory. LLDCanvas is built around exactly that loop: draw the diagram, defend the pattern, generate the code, and revise the concept you got wrong - all timed, all practiced against real interview questions.
¶02 · The Full Manifest
Seven entries. Read any one.
Click a row to expand it in place. Every entry links through to its own dedicated page for the full detail.
Model classes with typed attributes, methods, and visibility modifiers, then connect them with all seven real relationship types - association, aggregation, composition, inheritance, realization, dependency, and bidirectional - each rendered with the correct UML notation. Built for the exact vocabulary interviewers grade you on.
Write "Order has many OrderItem" or "PaymentStrategy implements Strategy" in plain English and watch it resolve into real classes and relationships instantly. It is how you think out loud in an interview - translated directly into notation, without breaking your train of thought to hand-place boxes.
Every real LLD round has a timer you cannot see and pressure you cannot rehearse away except by rehearsing it. Interview Mode reproduces both: a visible countdown, a structured problem brief, and a streak tracker that keeps you practicing on the days you would rather not.
Parking lots, elevators, rate limiters, ride-hailing systems, distributed caches - the actual questions asked at the companies that ask them, each with functional and non-functional requirements written the way an interviewer would state them, not a textbook.
SOLID principles, the 23 classic design patterns, core OOP concepts, and system-design fundamentals - each note built around a concrete analogy so the concept sticks, not just a definition to memorize the night before.
Generate real, runnable scaffolding from your class diagram and execute it in-browser against Python, Java, C++, C#, Go, Rust, TypeScript, and more - so the diagram you drew is provably a design that actually compiles, not just a picture.
Share a room and design together in real time - live cursors, named presence, and inline comments on any node. Built for mock interviews with a friend or a live pairing session, exactly the way the real thing happens over a video call.
¶03 · Why We Built This
“Most LLD prep is a PDF of questions and a blank whiteboard. We built the tool we wished we’d had - the diagram, the drill, and the review, in one place.”
Frequently asked questions
What is a Low-Level Design (LLD) interview?
An LLD interview - also called a machine coding round or object-oriented design round - asks you to design the internal classes, interfaces, and relationships of a system, like a parking lot or a ride-hailing app, using UML and object-oriented principles. It is a standard round at most product-based tech companies, usually graded on the design patterns and SOLID principles you apply, not just whether the code runs.
What is the difference between HLD and LLD interviews?
High-Level Design (HLD) covers system architecture - services, databases, load balancers, caching, and how they scale. Low-Level Design (LLD) goes one level deeper: the actual classes, interfaces, design patterns, and relationships inside a single service or module. Most interview loops test both, in separate rounds.
Which design patterns come up most often in LLD interviews?
Strategy, Factory, Singleton, Observer, Decorator, and Builder appear constantly, usually because a stated requirement - "support multiple payment methods," "notify users on status change" - maps directly onto one of them. LLDCanvas’s revision notes cover all 23 classic design patterns, each with a concrete analogy.
How should I prepare for a machine coding round?
Practice under a timer, out loud, the way the real round runs: read the requirements, identify the entities, choose relationships and patterns deliberately, then generate working code. LLDCanvas’s Interview Mode and 110+ practice problems are built specifically around that loop.
Which companies ask Low-Level Design interview questions?
Amazon, Uber, Flipkart, Swiggy, Ola, Walmart, and most Series B+ product companies run a dedicated LLD or machine coding round, often as the deciding round for SDE-2 and senior roles. Every problem in LLDCanvas’s library is tagged by the companies known to ask it.
Is LLDCanvas free to use?
Yes - the UML editor, Draft Notation, a subset of practice problems, and revision notes are free. Interview Mode, the full 110+ problem library, and multi-language code execution are part of the paid plan; see Pricing for details.