What is the difference between HLD and LLD?
HLD is the big picture (components, communication, tech stack, data flow). LLD is the detail (schemas, API contracts, logic, errors, edge cases). HLD settles architecture; LLD settles implementation.
Verify This Answer
Cross-check this information using these trusted sources:
More FAQs in HLD vs LLD: Interview Questions and Answers
HLD first, then LLD. You decide architecture before detailing implementation. LLD depends on the choices made in HLD.
Database schemas with types and indexes, API contracts (endpoints, methods, request/response shapes, status codes), internal logic, error cases, and edge cases. Enough for a developer to code without questions.
List them explicitly per endpoint: empty states, duplicates, race conditions, concurrent edits, large inputs. For each, document the behavior to implement. Do not leave edge cases implicit.
Still have questions?
Browse all our FAQs or reach out to our support team