Overview

Goals (ticketing-specific)

• Handle extreme burst traffic (on-sale moments)
• Prevent overselling under high contention
• Make payments safe under retries/out-of-order delivery
• Keep operational overhead low while scaling reliably

System at a glance

Key ideas

• Database is the source of truth (inventory correctness)
• Webhooks enqueue jobs; workers finalize transactions
• Idempotency everywhere (SQS is at-least-once; Stripe retries)