curl --request GET \
  --url https://panel.sendcloud.sc/api/v3/contracts/{id} \
  --header 'Authorization: Basic <encoded-value>'

{
  "data": {
    "id": 60,
    "carrier": {
      "code": "lettresuivie",
      "name": "Lettre Suivie"
    },
    "client_id": "sendcloud-1",
    "is_default_per_carrier": true,
    "state": "active",
    "type": "direct"
  }
}