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

# Availability updates

`offer.availability.changed` fires when availability flips between `InStock` and `OutOfStock`. Use it for back-in-stock and sold-out alerts.

Subscribe with this event from [Setup](/docs/guides/webhooks/setup.md).

A subscription with a `selection` currently receives one of these for every variation flip on that offer in the subscription's locale, whichever size or color moved. `subject.selection` is the configuration you pinned. `previous` and `current` are the availability before and after the flip.

```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
{
  "id": "8c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c9d",
  "timestamp": "2026-10-25T14:03:11.592000+00:00",
  "type": "offer.availability.changed",
  "data": {
    "subscription_id": "01JZK3V1M0T4QF3Y3Z0E5T6V7W",
    "subject": {
      "product_id": "2yh8WH5",
      "domain": "nike.com",
      "locale": { "language": "en", "country": "US", "currency": "USD" },
      "selection": null
    },
    "previous": "OutOfStock",
    "current": "InStock"
  }
}
```

`data.subject` names the offer. The `id` stays the same when a delivery is retried.

> [card] [Payload reference](/docs/product-subscription-webhooks.md)
>
> Full schema for `offer.availability.changed`.


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