Signed, deduplicable and retried with a stable event id.
Subscribe to order and delivery events. Verify HMAC-SHA256 over the raw body. Every raw body is HMAC-SHA256 signed and retried up to six times with the same event ID, body and signature.
order.paid
A buyer's payment was accepted.
order.failed
Payment or checkout processing failed.
order.refunded
The order was fully refunded.
delivery.completed
A line item was delivered successfully.
delivery.failed
A line-item delivery failed.
# Standard headers Sellix sets on every delivery X-Sellix-Event-Id: 7a2327ba-8655-45b4-a768-13e2112b2556 X-Sellix-Event: order.paid X-Sellix-Signature: 8f7a9a2b… Content-Type: application/json # The exact raw body covered by X-Sellix-Signature { "id": "7a2327ba-8655-45b4-a768-13e2112b2556", "object": "event", "event": "order.paid", "created_at": "2026-05-26T07:14:22Z", "data": { "order": { "uuid": "…", "total_cents": 4900, … } } }
Paste a payload + secret. We compute the signature live in your browser using the Web Crypto API - same algorithm our SDK uses on your server.
6 attempts per delivery10s → 30s → 2m → 10m → 1hX-Sellix-Signature against the exact raw request body.X-Sellix-Event-Id. Retries keep the same id and body.200 - it's a feature, not a duplicate.