Get Client by its external reference id

Example response

{
  "data": {
    "id": "<ULID>",
    "name": "Test GmbH",
    "ext_tool_id": 24,
    "info": "Some information about your Client.",
    "color": "#000000",
    "active": true,
    "acronym": "ACR",
    "image_id": "<ULID>",
    "demo_flag": true
  }
}