Webhook

shipments.replaced

All of a shipment's items moved to a new shipment, for example when a new label was bought for it, the seller added tracking from their own label, or Whatnot support changed its label. The previous shipment is usually cancelled. The body has both shipments. Requires read:shipments.

Headers

webhook-id
Type: stringFormat: uuid
required

Unique ID of the event. Retries of a delivery send the same ID, so use it to deduplicate.
webhook-timestamp
Type: integerFormat: int64
required

When this delivery attempt was sent, as a Unix timestamp in seconds. Each retry sends a new timestamp.
webhook-signature
Type: string
required

Space-separated signatures, each v1, followed by the base64 HMAC-SHA256 of {webhook-id}.{webhook-timestamp}.{body}, keyed with your webhook secret.

Body·ShipmentReplacedWebhookBody

required

application/json

data
Type: ShipmentReplacedData
required

The event's data. Its shape depends on the topic.

Properties: 2
seller_id
Type: string
required

The ID of the seller the event belongs to.
timestamp
Type: stringFormat: date-time
required

When the event happened, in ISO 8601. Stable across retries; the webhook-timestamp header is when each attempt was sent.
type
const:
shipments.replaced
required

The webhook topic.
version
const:
v2
required

The payload version.

Responses

200

Acknowledge delivery. Any 2XX status counts.
default

Fail delivery. Non-2XX statuses and timeouts are retried.

postshipments.replaced

{
  "type": "shipments.replaced",
  "timestamp": "2026-10-20T16:00:00.123Z",
  "data": {
    "previous_shipment": {
      "created_at": "2026-09-21T12:00:00.000Z",
      "dimensions": {
        "height": 1,
        "length": 6,
        "unit": "inch",
        "width": 4
      },
      "documents": {
        "bundled_url": "https://example.com/documents.pdf",
        "label_url": "https://example.com/label.pdf"
      },
      "dropoff_due": "2026-09-23T07:00:00.000Z",
      "fulfillment_method": "shipping",
      "hazardous_material": "not_hazardous",
      "id": "12345",
      "insurance": {
        "amount": {
          "amount": "25.00",
          "currency": "USD"
        },
        "contents": "Trading cards"
      },
      "recipient": {
        "display_name": "Card Collector",
        "id": "6789",
        "username": "cardcollector"
      },
      "required_actions": [],
      "seller_paid_shipping_cost": {
        "amount": "5.99",
        "currency": "USD"
      },
      "signature_required": false,
      "status": "label_generated",
      "tracking": {
        "carrier": "usps",
        "service": "usps_ground_advantage",
        "tracking_code": "9400111899223100012345"
      },
      "updated_at": "2026-09-21T13:00:00.000Z",
      "url": "https://www.whatnot.com/dashboard/shipments/U2hpcG1lbnROb2RlOjUxMjU0MTM5Mw==",
      "weight": {
        "unit": "ounce",
        "value": 4
      }
    },
    "replacement_shipment": {
      "created_at": "2026-09-21T12:00:00.000Z",
      "dimensions": {
        "height": 1,
        "length": 6,
        "unit": "inch",
        "width": 4
      },
      "documents": {
        "bundled_url": "https://example.com/documents.pdf",
        "label_url": "https://example.com/label.pdf"
      },
      "dropoff_due": "2026-09-23T07:00:00.000Z",
      "fulfillment_method": "shipping",
      "hazardous_material": "not_hazardous",
      "id": "12345",
      "insurance": {
        "amount": {
          "amount": "25.00",
          "currency": "USD"
        },
        "contents": "Trading cards"
      },
      "recipient": {
        "display_name": "Card Collector",
        "id": "6789",
        "username": "cardcollector"
      },
      "required_actions": [],
      "seller_paid_shipping_cost": {
        "amount": "5.99",
        "currency": "USD"
      },
      "signature_required": false,
      "status": "label_generated",
      "tracking": {
        "carrier": "usps",
        "service": "usps_ground_advantage",
        "tracking_code": "9400111899223100012345"
      },
      "updated_at": "2026-09-21T13:00:00.000Z",
      "url": "https://www.whatnot.com/dashboard/shipments/U2hpcG1lbnROb2RlOjUxMjU0MTM5Mw==",
      "weight": {
        "unit": "ounce",
        "value": 4
      }
    }
  },
  "version": "v2",
  "seller_id": "1234567"
}

No Body

Acknowledge delivery. Any 2XX status counts.

shipments.cancelled

Products