HLD vs. LLD (High-Level vs. Low-Level Design)
Both are 'design' interview rounds, especially in India, and recruiters often schedule the wrong one. HLD is the big picture: which services, databases, caches and queues a system needs and how they connect to handle scale. LLD is inside one component: the classes, interfaces and design patterns, written as code. Senior and staff candidates are judged mostly on HLD; mid-level candidates are often tested on LLD.
How to tell them apart on a resume
HLD (High-Level Design)
Architecture diagrams, scalability, load balancers, sharding, caching, 'designed the system for X million users' — architect, staff and senior roles.
LLD (Low-Level Design)
OOP, SOLID, design patterns, class diagrams, machine-coding rounds ('design a parking lot') — mid-level engineers who write most of the code.
The question that settles it
“In your last design work, were you deciding which services and databases the system needed, or designing the classes and code inside one service?”
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