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

# Add Contacts to Campaign

> Enroll one or more contacts into a campaign

## Request

### Path Parameters

<ParamField path="id" type="string" required>
  The campaign's unique ID (UUID)
</ParamField>

### Headers

```
Authorization: Bearer wbk_your_api_key_here
Content-Type: application/json
```

<Note>
  Requires an API key with the `campaigns:write` permission. Fires the `campaign.contacts_added` webhook event.
</Note>

### Body Parameters

<ParamField body="contact_ids" type="array" required>
  Array of contact UUIDs to enroll. Maximum 500 per request. Duplicates are silently skipped.
</ParamField>

<ParamField body="source" type="string">
  Optional free-form tag describing where these contacts came from (e.g., `list:cold-outreach-q2`, `import:csv-2026-04`). Stored on each enrollment for analytics.
</ParamField>

## Response

<ResponseField name="data" type="object">
  <Expandable title="properties">
    <ResponseField name="added" type="integer">
      Number of contacts newly enrolled
    </ResponseField>

    <ResponseField name="skipped" type="integer">
      Number of contacts already enrolled (no-op)
    </ResponseField>

    <ResponseField name="contact_ids" type="array">
      IDs of contacts that were newly added
    </ResponseField>
  </Expandable>
</ResponseField>

<CodeGroup>
  ```bash cURL theme={null}
  curl -X POST https://data.leadlex.com/functions/v1/api-gateway/v1/campaigns/cmp_abc123/contacts \
    -H "Authorization: Bearer wbk_your_api_key_here" \
    -H "Content-Type: application/json" \
    -d '{
      "contact_ids": [
        "123e4567-e89b-12d3-a456-426614174000",
        "223e4567-e89b-12d3-a456-426614174001"
      ],
      "source": "list:cold-outreach-q2"
    }'
  ```

  ```python Python theme={null}
  import requests

  API_KEY = "wbk_your_api_key_here"
  BASE_URL = "https://data.leadlex.com/functions/v1/api-gateway"
  CAMPAIGN_ID = "cmp_abc123"

  response = requests.post(
      f"{BASE_URL}/v1/campaigns/{CAMPAIGN_ID}/contacts",
      headers={
          "Authorization": f"Bearer {API_KEY}",
          "Content-Type": "application/json",
      },
      json={
          "contact_ids": [
              "123e4567-e89b-12d3-a456-426614174000",
              "223e4567-e89b-12d3-a456-426614174001",
          ],
          "source": "list:cold-outreach-q2",
      },
  )
  ```

  ```javascript JavaScript theme={null}
  const CAMPAIGN_ID = 'cmp_abc123';

  await fetch(
    `https://data.leadlex.com/functions/v1/api-gateway/v1/campaigns/${CAMPAIGN_ID}/contacts`,
    {
      method: 'POST',
      headers: {
        'Authorization': 'Bearer wbk_your_api_key_here',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        contact_ids: [
          '123e4567-e89b-12d3-a456-426614174000',
          '223e4567-e89b-12d3-a456-426614174001',
        ],
        source: 'list:cold-outreach-q2',
      }),
    }
  );
  ```
</CodeGroup>

### Example Response

```json theme={null}
{
  "data": {
    "added": 2,
    "skipped": 0,
    "contact_ids": [
      "123e4567-e89b-12d3-a456-426614174000",
      "223e4567-e89b-12d3-a456-426614174001"
    ]
  }
}
```

## Errors

| Status | Code                       | Description                                |
| ------ | -------------------------- | ------------------------------------------ |
| 400    | `too_many_contacts`        | More than 500 contacts in a single request |
| 400    | `missing_required_field`   | `contact_ids` missing or empty             |
| 401    | `invalid_key`              | Invalid or expired API key                 |
| 403    | `insufficient_permissions` | Missing `campaigns:write` permission       |
| 404    | `campaign_not_found`       | No campaign with this ID                   |
| 429    | `rate_limited`             | Rate limit exceeded                        |