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EngineeringMarch 28, 2026· 11 min read

Webhook Delivery Guarantees: At-Least-Once vs Exactly-Once Semantics

Most API platforms promise webhook delivery but rarely guarantee it. This deep-dive covers retry strategies, idempotency keys, exponential backoff, and how to build a webhook infrastructure with 99.99% delivery confidence.

Handling Failures

Network drops and receiver downtime are inevitable. A robust webhook system must implement exponential backoff and rely on idempotency keys to ensure messages are delivered without duplication.

About the Author

M
Marcus WebbHead of Product

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Webhook Delivery Guarantees: At-Least-Once vs Exactly-Once Semantics