Why webhook integrations fail
Webhooks are the backbone of modern system integration — but they fail in predictable ways. Understanding these failure modes upfront lets you build integrations that handle them gracefully rather than silently losing data.
The fundamental problem: delivery guarantees
Most webhooks are delivered at-least-once — the sending system may retry if it does not receive a 200 response. This means your webhook handler must be idempotent: processing the same event twice should have the same result as processing it once.
Implement idempotency by storing a record of processed event IDs. Before processing any webhook, check whether the event ID has been seen before. If so, return 200 immediately without reprocessing.
The acknowledgement pattern
Webhook handlers should follow the acknowledge-then-process pattern:
1. Validate the payload and verify the signature 2. Return 200 immediately 3. Process the event asynchronously via a job queue
This prevents timeout failures (the sending system gives up if your handler takes too long) and allows you to retry failed processing without the sending system retrying the delivery.
Signature verification
Always verify webhook signatures. Most webhook providers sign their payloads with HMAC-SHA256. Compare the signature in the request header against the HMAC of the raw request body using your secret key. Use a timing-safe comparison to prevent timing attacks.
The retry strategy
For outbound webhooks you are delivering, implement exponential backoff with jitter. A recipient system that is temporarily down should receive retries at increasing intervals — not hammered with retries every second. After a configured number of retries (typically 5–10), move the event to a dead-letter queue for manual review.
Observability
Every webhook event should be logged with:
- Event ID and type
- Source system and timestamp
- Processing status (received, queued, processed, failed)
- Processing duration
- Any error messages
This makes debugging integration failures possible and gives you visibility into processing latency and error rates.