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Use SSE when a connected client needs low-latency progress. Use webhooks when your backend needs durable asynchronous delivery. Many products use both.

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Example applications

  • Update a progress UI while a mission runs.
  • Start a downstream job only after a terminal event.
  • Route an approval-needed event to an internal review queue.
  • Reconcile a delivery after a network timeout without repeating the effect.
  • Populate a warehouse from immutable event IDs and ordered sequences.

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Delivery rules

  1. Verify a webhook over the exact raw body before parsing JSON.
  2. Reject stale timestamps and invalid signatures.
  3. Persist the event before returning 2xx.
  4. Deduplicate by immutable event ID.
  5. Process run events by sequence rather than arrival order.
  6. Resume SSE with the last event ID.
  7. Treat EOF before terminal as incomplete.

Signed webhook tutorial

Implement verification, persistence, replay, and cleanup.

Event troubleshooting

Diagnose signatures, ordering, duplicate delivery, and stream gaps.
Last modified on August 14, 2026