Build a Webhook Dispatcher

HMAC signing with exponential backoff

Challenge 6 of Async & MessagingIntermediate~50 min

Deliver events to other people's servers reliably, even when they're flaky. Build the pieces every webhook system needs: an HMAC signature so receivers can trust the payload, an exponential-backoff retry schedule, a dispatcher that retries failed deliveries, and idempotent dispatch so a redelivery never fires the same event twice. The machinery behind Stripe, GitHub, and Slack webhooks.

4 steps

1. 1Signing the Payload
2. 2Verifying Safely
3. 3Exponential Backoff
4. 4Dispatch with Retries and Idempotency