Webhook delivery system
Design a webhook-delivery system that reliably delivers event notifications to millions of customer-owned HTTP endpoints. You generate ~500k events/sec; each customer endpoint must receive its events in order, at-least-once, with retries and exponential backoff when their server is down or slow. A single broken/slow endpoint must not back up delivery for everyone else, and customers need a way to replay missed events. How do you deliver at scale while isolating slow/failing destinations and guaranteeing ordering + retries?
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.
Clarify5:30 left
Estimate5:30 planned
Design16:30 planned
Deep dive13:30 planned
Failure9:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.