> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sequencehq.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Webhook events

> Reference for the events Sequence sends, the payload envelope, signature header, and delivery behaviour.

This page is the reference for what Sequence sends and how. For a step-by-step integration walkthrough, see [Set up webhooks](/reference/webhooks).

## Request format

Sequence delivers webhooks as `POST` requests with `Content-Type: application/json`. Every payload has the same envelope:

```typescript theme={null}
{
  notificationType: string;
  sequenceAccountId: string;
  resourceType?: string;
  resourceId?: string;
  resource?: Record<string, any>;
}
```

The `resource` field contains the state of the resource that triggered the event.

### Example payload

A `BILLING_SCHEDULE_CREATED` delivery looks like this. The `prices` and `phases` arrays are simplified for readability; in real deliveries they contain the full pricing and phase structure for the schedule.

```json theme={null}
{
  "notificationType": "BILLING_SCHEDULE_CREATED",
  "sequenceAccountId": "019e6eb6-db30-7cf2-8017-06a5a2859e13",
  "resourceType": "BillingScheduleResponse",
  "resourceId": "019e6eb6-cd26-74eb-808b-e7a37f1c4ef1",
  "resource": {
    "id": "019e6eb7-0c24-765b-8446-6fb074f018d7",
    "status": "DRAFT",
    "startDate": "2026-04-27",
    "endDate": "2027-04-26",
    "customerId": "019e6eb7-353e-7ddf-a5ae-75f2d9509d6b",
    "recurrenceDayOfMonth": 1,
    "autoIssueInvoices": false,
    "rollUpBilling": false,
    "defaultDueDateDays": 30,
    "prices": [],
    "phases": [],
    "taxRates": [],
    "attachmentAssets": [],
    "integrationIds": [],
    "createdAt": "2026-04-27T17:04:11.601533Z",
    "updatedAt": "2026-04-27T17:04:11.601533Z"
  }
}
```

## `Sequence-Signature` header

Every webhook includes a `Sequence-Signature` header containing a timestamp and an HMAC signature:

```
Sequence-Signature: t=1748866120822,s=6be6887a470c20978427ff89941ebecb83b2804ceed66fd93b3afc00de2e9f11
```

* `t` is the delivery timestamp, in Unix milliseconds.
* `s` is an HMAC-SHA256 signature of `${t}.${rawBody}`, computed using the webhook's signing secret.

The timestamp is part of the signed payload, so receivers can reject deliveries with a stale `t` to mitigate replay attacks.

For working verification code, see [Verify the signature](/reference/webhooks#verify-the-signature) in the integration guide.

## Delivery

* **Acknowledgement.** Sequence considers any `2xx` response a successful delivery.
* **Retries.** Any non-`2xx` response causes Sequence to retry. Retries continue for up to **24 hours**, with exponential backoff.

New event types may be added over time. Handlers should accept and ignore types they don't recognise.

## Event catalog

| Event                       | Resource type   | Triggered when                      |
| --------------------------- | --------------- | ----------------------------------- |
| `CUSTOMER_CREATED`          | Customer        | A customer is created               |
| `CUSTOMER_UPDATED`          | Customer        | A customer is updated               |
| `CUSTOMER_ARCHIVED`         | Customer        | A customer is archived              |
| `INVOICE_CREATED`           | Invoice         | An invoice is created               |
| `INVOICE_ISSUED`            | Invoice         | An invoice is issued                |
| `INVOICE_UPDATED`           | Invoice         | An invoice is updated               |
| `BILLING_SCHEDULE_CREATED`  | BillingSchedule | A billing schedule is created       |
| `BILLING_SCHEDULE_UPDATED`  | BillingSchedule | A billing schedule is updated       |
| `BILLING_SCHEDULE_ARCHIVED` | BillingSchedule | A billing schedule is archived      |
| `CREDIT_NOTE_CREATED`       | CreditNote      | A credit note is created            |
| `CREDIT_NOTE_UPDATED`       | CreditNote      | A credit note is updated            |
| `CREDIT_NOTE_ISSUED`        | CreditNote      | A credit note is issued             |
| `QUOTE_PUBLISHED`           | Quote           | A quote is published                |
| `QUOTE_SIGNED`              | Quote           | A quote is signed                   |
| `QUOTE_ACCEPTED`            | Quote           | A quote is accepted                 |
| `MERCHANT_UPDATED`          | Merchant        | Merchant-level settings are updated |