11. Design a Container Orchestrator
Reconcile desired workloads, schedule containers and recover from failed nodes safely.
ClassicHard
Guided practice
Start with a template. Work through each step. Ask Coach when you need a second opinion.
Designs with worked examples 6
Ordered by design numberCompany tags are community-reported. Counts on cards show how many people reported that design.
ReconciliationClear filters
40. Design an Ad Click Aggregator
Count every ad click once, fast enough to chart live and exactly enough to bill. One-hour interview boards for junior, senior and staff: requirements, data layer, low-level design and what goes wrong at every component.
ClassicMedium52. Design a Payment System like Stripe
Charge cards through the networks exactly once: idempotency keys, a card vault, timeouts as unknowns, signed webhooks, a double-entry ledger and reconciliation. One-hour boards for junior, senior and staff, with the theory behind them.
ClassicMedium53. Design a Stock Trading App like Robinhood
Live prices to five million phones through per-symbol pub/sub, and market and limit orders over FIX that are never lost, sent twice or overspent.
ClassicMedium89. Design a Donations Website for a Charity Event
Ten charities, three days, $100 M: charge through a third-party processor exactly once, queue the broadcast spikes, keep live totals on sharded counters. One-hour boards for junior, senior and staff, with the theory behind them.
ClassicMedium98. Design a Double-Entry Ledger
Record every money movement as balanced, append-only entries, exactly once, with holds, payouts and reconciliation.
ClassicMedium