curl --request POST \
  --url https://api.blockradar.co/v1/wallets/{walletId}/withdraw/sign \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "assets": [
    {
      "address": "0xRecipient1Address",
      "amount": "10.5",
      "id": "{{assetId1}}",
      "reference": "sign-001"
    },
    {
      "address": "0xRecipient2Address",
      "amount": "25.0",
      "id": "{{assetId2}}",
      "reference": "sign-002"
    }
  ]
}
'

{
  "data": {
    "errors": [],
    "success": [
      {
        "hash": "0xsignedhash1...",
        "id": "tx-uuid-1",
        "signedTransaction": "0xf86c..."
      },
      {
        "hash": "0xsignedhash2...",
        "id": "tx-uuid-2",
        "signedTransaction": "0xf86d..."
      }
    ]
  },
  "message": "Batch withdrawal signed (2/2 successful)",
  "statusCode": 200
}