HelloInterview - Low-Level Design in a Hurry

The focus of the interview is on code organization: What are the right objects? How do they interact? What methods do they expose? Can the design be extended without rewriting everything?

Modern production systems favor composition over inheritance, simple state over deep hierarchies, and pragmatism over pattern worship.

You’ll still learn the patterns that matter, but only the ones that actually show up in real interviews and real codebases.

How its different than system design interview?

In a low-level design interview, instead of drawing services, you write the code structure for a single part of the system, usually in pseudocode. For that same ride sharing example, you might design the Trip class, the TripState enum, the PricingCalculator interface, and how these objects collaborate. The discussion is about methods, relationships, data models, and state transitions, not how to scale the fleet to millions of users.

Interviewers want to see whether you can turn a small, well-scoped problem into a clean, maintainable code structure. They are testing your ability to decompose a system, express clear classes, and design code that a real team would want to work with.