System designMediumsd-g555

Subject WebhooksLevel Entry–Mid~30 minCommon in Networking & APIs interviewsIndustries Software development, Technology

Question

Design webhook delivery for a small app that lets customers register a URL to be notified when an event happens (e.g. an order is placed). When an event fires, you POST it to the customer's URL. Customer endpoints are sometimes slow or temporarily down. Volume is modest. Describe how you deliver reliably without blocking your own app and what you do when a customer's endpoint fails.

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.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.