Mock interviews¶
Six full transcripts - three HLD, three LLD - with the clock running: what the interviewer says, what the candidate says, draws and writes at each minute, and how the diagram evolves from a v1 skeleton to the version after the deep dives. Each mock ends with a rubric showing what below-bar, SDE2 and exceeds look like, with quotes from the transcript, plus three variants to redo alone. Read the matching case study or problem first, then attempt the prompt yourself before reading the transcript.
Tiers: P0 must be solid before any interview, P1 is expected of a strong SDE2, P2 is stretch material for when the rest is done.
Start here (P0)¶
- Mock HLD interview: news feed
- Mock HLD interview: chat system
- Mock HLD interview: Ticketmaster
- Mock LLD interview: parking lot
- Mock LLD interview: elevator system
- Mock LLD interview: movie ticket booking
All pages¶
| # | Page | Tier | Covers |
|---|---|---|---|
| 1 | Mock HLD interview: news feed | P0 | Read-heavy fan-out archetype. Fan-out decision, cache design, ranking. |
| 2 | Mock HLD interview: chat system | P0 | Real-time stateful archetype. WebSocket state, ordering, delivery receipts, group fan-out. |
| 3 | Mock HLD interview: Ticketmaster | P0 | Transactional contended-inventory archetype. Concurrency, holds with TTL, waiting room, payment idempotency. |
| 4 | Mock LLD interview: parking lot | P0 | Resource-allocation archetype. Canonical Amazon OOD; Strategy and Factory; concurrency at gates; shows the order methods are written and… |
| 5 | Mock LLD interview: elevator system | P0 | Control-system archetype. State + Strategy + Mediator; simulation; scheduling trade-offs. |
| 6 | Mock LLD interview: movie ticket booking | P0 | Contended-booking archetype. Seat locking, state machines, payment race. |