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

# Add Companies To List

> Bulk-add static company membership to an accounts list

Adding a company already on the list is a no-op, so this is safe to retry
over a selection that partly overlaps what's already there.

## Path Parameters

<ParamField path="listId" type="string" required />

## Body

<ParamField body="company_ids" type="string[]" required>
  Company UUIDs, from `company_id` on [List Accounts](/api-reference/list-accounts).
</ParamField>

<RequestExample>
  ```bash cURL theme={null}
  curl -X POST "https://api.clustr-ai.com/api/public/lists/l1a2b3c4-.../companies" \
    -H "Authorization: Bearer YOUR_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{"company_ids": ["9c4d5e6f-...", "7a1b2c3d-..."]}'
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  {
    "success": true,
    "data": { "message": "Companies added to list", "added": 2 }
  }
  ```

  ```json 404 theme={null}
  {
    "success": false,
    "error": { "message": "list not found", "code": "NOT_FOUND" }
  }
  ```
</ResponseExample>