How to Build Reliable Webhook Handlers: Retries, Idempotency, and Deduplication

Webhooks commonly fail in production due to network timeouts, slow endpoints, and duplicate deliveries, as senders like Stripe and GitHub retry any request that does not receive a timely 2xx response. This at-least-once delivery model means receivers can process the same event multiple times, making idempotency a critical responsibility of the handler, not the sender. The recommended fix is to store a stable provider-supplied event ID in a database with a unique constraint, using an atomic insert to reject duplicates before any side effects are applied. Wrapping both the deduplication claim and the business logic in a single database transaction prevents partial failures from causing inconsistent state. Applying these patterns — fast acknowledgment, database-backed deduplication, and transactional side effects — eliminates most categories of webhook-related production incidents.