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

# Update Contact Topic Subscription

> Subscribe or unsubscribe a contact from a topic.

## Endpoint

`PUT /contacts/:contact_id/topics/:topic_id`

## Request body

```json theme={null}
{
  "is_subscribed": true
}
```

## Response

```json theme={null}
{
  "data": {
    "id": "0df0fc92-89f2-4f23-a9e6-e9da2f3c1685",
    "contact_id": "c671f89b-3ec1-4c58-9ad2-4ef8c2917cda",
    "topic_id": "8c3c4d0e-f7f3-4d7f-92ae-b1498f6a2fa9",
    "is_subscribed": true,
    "subscribed_at": "2026-06-08T15:12:00.000Z",
    "unsubscribed_at": null
  }
}
```

Successful updates also emit `sendrealm.topic.subscribed` or `sendrealm.topic.unsubscribed`.