Overage incurred

Fires on the first signal that takes a customer's usage beyond their credit balance since their latest grant of credits in that currency (a period's allowance or a top-up), so the credits beyond it are billed at their plan's price per extra credit. It fires once per grant, not for every signal in overage. Like the other credit events, it fires only for usage as it happens, not for replays or for backfilled signals more than a week old. data.overage is the balance just after that signal, with available below zero, overageCredits, how many credits over the balance they are, and the orderId and signalId involved.

Headers

X-Webhook-Signature
Type: string
required

t=<timestamp>,s=<signature>. t is when the delivery was signed, in Unix milliseconds; each attempt is signed afresh, so a retry has a new t. s is the Base64 (standard alphabet, padded) HMAC-SHA256 of the string <t>.<raw request body>, keyed with your signing secret: the whole whsec_… string as UTF-8. To verify, recompute it over the raw body exactly as received and compare in constant time, then reject a t too far from now (5 minutes is a good limit) so an old delivery can't be replayed. s can end in =, so split each part on its first = only.

Body

required

application/json

Every delivery's body.

- data
  Type:
  required
  
  The event's payload, under the key the event names.
  
  Properties: 1
- event
  enum
  const:
  billing-overage-incurred
  required
  
  A billing event you can receive. billing-invoice-paid, billing-invoice-posted, billing-invoice-refunded, billing-checkout-created, billing-checkout-completed, billing-checkout-expired, billing-payment-succeeded, billing-payment-failed, billing-credits-depleted, billing-overage-incurred and billing-credit-cap-reached; each is described in the Webhooks section.
  
  values
  billing-invoice-paid
  billing-invoice-posted
  billing-invoice-refunded
  billing-checkout-created
  billing-checkout-completed
  billing-checkout-expired
  billing-payment-succeeded
  billing-payment-failed
  billing-credits-depleted
  billing-overage-incurred
  billing-credit-cap-reached
- id
  Type: string
  required
  
  The delivery's ID (whd_…), the same on every retry of it: keep the IDs you've handled and ignore a delivery whose ID you've seen. A test delivery has an ID of its own.
- isTest
  Type: boolean
  required
  
  true for a delivery sent with Send a test delivery, whose data is placeholder; false otherwise.
- timestamp
  Type: stringFormat: date-time
  required
  
  When the event happened, and the delivery was first queued; the same on every retry.

Responses

200

Return any 2xx to acknowledge. Any other status, a redirect (redirects aren't followed), or no answer within 5 seconds is a failed attempt, recorded in the webhook's lastStatus. A failed delivery is retried 1 minute, 5 minutes, 30 minutes, 2 hours and then 12 hours after each failed attempt in turn (retries are sent by a sweep that runs every minute, so each can be up to a minute later), and dropped after the sixth failed attempt. A retry carries the same id and timestamp and goes to the webhook's current URL; a delivery whose webhook has since been switched off is dropped. Because of retries, an event can arrive more than once or after a later one: use id to ignore repeats. The response body is ignored.

postbilling-overage-incurred

{
  "id": "whd_Hp1Xt4Nf7Qj3Bs9Y",
  "event": "billing-overage-incurred",
  "timestamp": "2026-11-21T16:02:51.093Z",
  "isTest": false,
  "data": {
    "overage": {
      "customerId": "cus_Q2x9vB7mK4pT1sLw",
      "externalCustomerId": "acme-legal",
      "creditsCurrencyId": "cc_jC18u1xkf7CdKYcL",
      "currencyKey": "credits",
      "currencyName": "Credits",
      "available": -1,
      "used": 51,
      "total": 50,
      "periodStart": "2026-11-01T00:00:00.000Z",
      "periodEnd": "2026-12-01T00:00:00.000Z",
      "overageCredits": 1,
      "orderId": "ord_8Jt3Vw0Ym5Ln2Qp7",
      "signalId": "sig_Hq7Vn2Lx9Tb4Wc0P"
    }
  }
}

No Body

Return any 2xx to acknowledge. Any other status, a redirect (redirects aren't followed), or no answer within 5 seconds is a failed attempt, recorded in the webhook's lastStatus. A failed delivery is retried 1 minute, 5 minutes, 30 minutes, 2 hours and then 12 hours after each failed attempt in turn (retries are sent by a sweep that runs every minute, so each can be up to a minute later), and dropped after the sixth failed attempt. A retry carries the same id and timestamp and goes to the webhook's current URL; a delivery whose webhook has since been switched off is dropped. Because of retries, an event can arrive more than once or after a later one: use id to ignore repeats. The response body is ignored.

Credits depleted

Credit cap reached