How to Build Reliable Webhook Pipelines Using Dead-Letter Queues and Idempotency

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Webhook delivery systems commonly operate on at-least-once delivery guarantees, meaning duplicate events are a known risk acknowledged by providers like Stripe and AWS SQS, making consumer-side deduplication essential. The recommended pattern involves verifying provider signatures, extracting event IDs, and storing them in a unique-indexed idempotency table before processing asynchronously. Dead-letter queues (DLQs) in AWS SQS should be configured with longer retention periods than source queues — at least 14 days, with 30 days suggested for payment-related webhooks — since message age counts from original enqueue time, not DLQ arrival. Teams are advised to alert when DLQ depth exceeds around 10 events, as a small backlog often signals a handler bug or failing dependency before a larger outage becomes visible. For teams preferring not to build this infrastructure from scratch, specialized vendors such as Hookdeck, Svix, and InstaWebhook offer varying levels of managed webhook reliability tooling.

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