Webhook Reliability: Delivery Guarantees Your Clients Can Count On
Webhooks Are a Distributed Systems Problem
A webhook looks like a simple callback and is actually a distributed systems problem in disguise. The receiver can be down, slow, or flaky, and the network can drop or duplicate a delivery at any time.
Treating webhooks as fire-and-forget is how events silently vanish. Reliable delivery takes deliberate design.
At-Least-Once, and Why It Matters
Exactly-once delivery over an unreliable network is effectively impossible, so the honest guarantee is at-least-once: keep retrying until the receiver acknowledges.
That means receivers must be idempotent, able to handle the same event twice without double-processing. Ship an event id and make consumers dedupe on it.
Retry With Backoff and a Ceiling
Naive retries hammer a struggling receiver and make things worse. Exponential backoff with jitter spreads the load and gives a recovering endpoint room to breathe.
Cap the retries and define what happens when they're exhausted, so a permanently dead endpoint doesn't retry forever.
Dead-Letter and Replay
Events that can't be delivered shouldn't disappear. A dead-letter queue captures them, and a replay mechanism lets you redeliver once the receiver is healthy again.
This turns a receiver outage from lost data into a recoverable pause.
