# February 3, 2026 

** February 03, 2026 Karbon API release introduces the CustomField webhook type and a new filter parameter for the WorkItems endpoint. **
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## New CustomField Webhook Type

We have introduced a new webhook type for `CustomField` updates. You can now subscribe to events that notify you when Custom Field values are created or updated.

To subscribe to changes in Custom Field values, make a `POST` request to  `/v3/WebhookSubscriptions` using the type `CustomField` in the payload.

For example:

```json
{
    "TargetUrl": "https://example.com/webhook",
    "WebhookType": "CustomField"
}
```

Note: You will receive a webhook for each Custom Field value that is added or updated. This may result in a large number of notifications.

## New WorkScheduleKey Filter for WorkItems Endpoint

You can now filter Work Items by their associated Work Schedule. Use the `WorkScheduleKey` parameter in a `GET` request to the `/v3/WorkItems` endpoint.

For example: `/v3/WorkItems?$filter=WorkScheduleKey eq 'FXcWYY9xZfd'`