Reliable webhooks: idempotency, retries, and monitoring

Duplicate events are expected

A sender may not know whether the destination processed a request. The connection can fail after processing but before acknowledgment, so the sender delivers the event again.

Consumers should therefore assume at-least-once delivery. Every event needs a stable identifier recorded before side effects such as creating an order or charging a customer. A previously processed ID should be acknowledged without repeating the action.

Retries need a policy

Rapid repeated attempts increase load during an outage. Use progressively longer intervals, or backoff, with a small amount of randomness so thousands of events do not return together.

Temporary errors can return to the queue. Permanent errors, including invalid payloads, belong in a review queue instead of an infinite retry loop.

What each execution should log

• Event ID and source
• Received and completed timestamps
• HTTP status and error category
• Attempt number
• Affected business record
• Total processing time

Alerts that support action

Do not alert on every isolated error. Track error rate, queue depth, oldest event age, and dead-letter volume. Assign owners and document a replay procedure that preserves idempotency.

A simple dashboard should answer three questions: is the flow healthy, is it delayed, and which events need human action?

Conclusion

Reliability comes from making failures visible and recoverable. Add event IDs, a processing ledger, backoff retries, and an exception queue before increasing integration volume.