Top 32 System Design Questions

High-level design is the architecture round: services, databases, caching, load balancing, how the system scales and where it fails. Low-level design is the machine coding round: classes, interfaces and object relationships for a single component. This sheet splits them because they are separate interviews with separate skills — 22 HLD problems and 10 LLD problems.

Usually not a full HLD round, though LLD and machine coding do appear in fresher loops at some product companies. It becomes standard from around two to three years of experience, which makes it the round most worth preparing before you start looking for your second job rather than your first.

Clarify requirements and constraints first, then estimate scale, then define the API and data model, then draw the architecture, then discuss bottlenecks and trade-offs. The mistake that loses rounds is jumping to a diagram before agreeing what is actually being built.

Fewer than people expect. The 32 problems here recur constantly and reuse the same building blocks — caching, sharding, queues, consistency trade-offs. Understanding ten deeply beats skimming forty, because interviewers push on the trade-offs rather than the diagram.

Yes, in a role-appropriate form. Frontend interviews increasingly include a frontend system design round — component architecture, state management, rendering strategy and performance. Data and ML roles get pipeline and serving design. The framing changes; the reasoning does not.