> ## 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 List

> Add one or more contacts to an existing list

## Request

### Path Parameters

<ParamField path="id" type="string" required>
  List UUID
</ParamField>

### Headers

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

### Body Parameters

<ParamField body="contact_ids" type="array" required>
  Array of contact UUIDs to add to the list
</ParamField>

## Response

<ResponseField name="data" type="object">
  Operation result

  <Expandable title="properties">
    <ResponseField name="added" type="integer">
      Number of contacts successfully added
    </ResponseField>

    <ResponseField name="list_id" type="string">
      The list UUID
    </ResponseField>

    <ResponseField name="contact_count" type="integer">
      Total number of contacts now in the list
    </ResponseField>
  </Expandable>
</ResponseField>

<CodeGroup>
  ```bash cURL theme={null}
  curl -X POST \
    https://data.leadlex.com/functions/v1/api-gateway/v1/lists/abc-123/contacts \
    -H "Authorization: Bearer wbk_your_api_key_here" \
    -H "Content-Type: application/json" \
    -d '{
      "contact_ids": [
        "123e4567-e89b-12d3-a456-426614174000",
        "789e0123-e45b-67c8-a901-234567890abc"
      ]
    }'
  ```

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

  API_KEY = "wbk_your_api_key_here"
  BASE_URL = "https://data.leadlex.com/functions/v1/api-gateway"
  LIST_ID = "abc-123"

  headers = {
      "Authorization": f"Bearer {API_KEY}",
      "Content-Type": "application/json"
  }

  data = {
      "contact_ids": [
          "123e4567-e89b-12d3-a456-426614174000",
          "789e0123-e45b-67c8-a901-234567890abc"
      ]
  }

  response = requests.post(
      f"{BASE_URL}/v1/lists/{LIST_ID}/contacts",
      headers=headers,
      json=data
  )

  result = response.json()["data"]
  print(f"Added {result['added']} contacts to list")
  ```

  ```javascript JavaScript theme={null}
  const LIST_ID = 'abc-123';

  const response = await fetch(
    `https://data.leadlex.com/functions/v1/api-gateway/v1/lists/${LIST_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',
          '789e0123-e45b-67c8-a901-234567890abc'
        ]
      })
    }
  );

  const { data } = await response.json();
  console.log(`Added ${data.added} contacts`);
  ```
</CodeGroup>

### Example Response

```json theme={null}
{
  "data": {
    "added": 2,
    "list_id": "abc12345-678d-90ef-1234-567890abcdef",
    "contact_count": 47
  }
}
```

## Duplicate Handling

<Note>
  If a contact is already in the list, it will be silently skipped (not an error). The `added` count reflects only newly added contacts.
</Note>

### Example with Duplicates

If you try to add 5 contacts but 2 are already in the list:

```json theme={null}
{
  "data": {
    "added": 3,
    "list_id": "abc-123",
    "contact_count": 50
  }
}
```

## Bulk Operations

You can add up to 100 contacts in a single request:

```python theme={null}
# Add 100 contacts at once
contact_ids = [...]  # List of up to 100 UUIDs
response = requests.post(
    f"{BASE_URL}/v1/lists/{LIST_ID}/contacts",
    headers=headers,
    json={"contact_ids": contact_ids}
)
```

<Warning>
  Requests with more than 100 contact IDs will be rejected with a validation error.
</Warning>

## Errors

| Status | Code                       | Description                              |
| ------ | -------------------------- | ---------------------------------------- |
| 400    | `validation_error`         | Invalid contact IDs or exceeds 100 limit |
| 401    | `invalid_key`              | Invalid API key                          |
| 403    | `insufficient_permissions` | Missing `write` permission               |
| 404    | `not_found`                | List not found or not in your workspace  |
| 429    | `rate_limited`             | Rate limit exceeded                      |

### Example Error (Invalid Contact ID)

```json theme={null}
{
  "error": {
    "code": "validation_error",
    "message": "One or more contact IDs are invalid or not in your workspace",
    "details": {
      "invalid_ids": ["not-a-real-uuid"]
    }
  }
}
```