Glossary
Dead-Letter Queue (DLQ)
A holding area for webhooks that couldn't be delivered or processed after all retries — so failed events are preserved for inspection instead of silently lost.
When a webhook fails every retry — your endpoint was down for the whole 3-day window, or the handler kept throwing — the event has to go somewhere. A dead-letter queue is that somewhere: a durable store of undeliverable or unprocessable events, kept for manual review and later replay.
Without a DLQ, exhausted events vanish. You discover the loss weeks later when reconciliation shows missing orders. With one, you get a list of exactly what failed, the error, and the original payload — then replay them once the bug is fixed.
DLQs live on both sides: gateways (Hookdeck, EventBridge) offer them for outbound delivery, and you can build a consumer-side one — on any handler exception, write the raw event to a failed_webhooks table instead of returning non-2xx forever.
How HookSense helps
HookSense keeps full searchable history of every callback, including ones your handler rejected — so an agent can `list_callbacks`, inspect a failure, and `replay_callback` once you've shipped a fix. A dedicated dead-letter view is coming soon.
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