Handling Supplier Inventory Feed Delays and Failures (Preventing Overselling) System Design
A complete, beginner-to-production system design walkthrough for handling supplier inventory feed delays and failures without ever overselling: circuit breakers, safety stock buffers, Kafka-backed ingestion pipelines, reservation with optimistic locking, reconciliation jobs, and end-to-end monitoring, illustrated with inline architecture and sequence diagrams and Java code.
Designing a Real-Time A/B Testing System for Checkout Flows
A complete, beginner-to-production system design walkthrough for a real-time checkout A/B testing platform: deterministic edge-resolved bucketing, async Kafka-backed event ingestion, sequential-testing-safe statistics, guardrail-driven auto kill switches, and everything else needed to safely measure the effect of checkout-flow variants at a million-plus requests per minute without ever slowing checkout down.
Designing a Bulk Payroll Payment Processing System
A complete, beginner-to-production system design walkthrough for a bulk payroll payment processing system that pays 50,000 employees the correct amount, exactly once, every pay period — using idempotency keys, the Saga pattern, the outbox pattern, chunk-level checkpointing, and banking-rail reconciliation at platform scale.