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POST
/
v1
/
wallets
/
{walletId}
/
addresses
/
{addressId}
/
contracts
/
write
/
sign
Child Address Write Sign-Only
curl --request POST \
  --url https://api.blockradar.co/v1/wallets/{walletId}/addresses/{addressId}/contracts/write/sign \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "calls": [
    {
      "abi": [
        {
          "constant": false,
          "inputs": [
            {
              "name": "_to",
              "type": "address"
            },
            {
              "name": "_value",
              "type": "uint256"
            }
          ],
          "name": "transfer",
          "outputs": [],
          "payable": false,
          "stateMutability": "nonpayable",
          "type": "function"
        }
      ],
      "address": "0x337610d27c682E347C9cD60BD4b3b107C9d34dDd",
      "method": "transfer",
      "parameters": [
        "0x2455eC6700092991Ce0782365A89d5Cd89c8Fa22",
        "10000"
      ]
    },
    {
      "abi": [
        {
          "constant": false,
          "inputs": [
            {
              "name": "_to",
              "type": "address"
            },
            {
              "name": "_value",
              "type": "uint256"
            }
          ],
          "name": "transfer",
          "outputs": [],
          "payable": false,
          "stateMutability": "nonpayable",
          "type": "function"
        }
      ],
      "address": "0x337610d27c682E347C9cD60BD4b3b107C9d34dDd",
      "method": "transfer",
      "parameters": [
        "0x2455eC6700092991Ce0782365A89d5Cd89c8Fa22",
        "10000"
      ]
    }
  ]
}
'
{ "data": { "amlScreening": {}, "amount": null, "amountPaid": null, "amountUSD": "0.00", "asset": null, "assetSwept": null, "assetSweptAmount": null, "assetSweptAt": null, "assetSweptGasFee": null, "assetSweptHash": null, "assetSweptRecipientAddress": null, "assetSweptSenderAddress": null, "blockHash": null, "blockNumber": null, "blockchain": { "createdAt": "2024-05-27T14:31:14.966Z", "derivationPath": "m/44'/60'/0'/0", "id": "74733889-4ecd-403e-9840-94e87c043f24", "isActive": true, "isEvmCompatible": true, "isL2": true, "name": "base", "slug": "base", "symbol": "eth", "tokenStandard": null, "updatedAt": "2024-11-26T20:04:13.945Z" }, "chainId": null, "confirmations": null, "confirmed": true, "createdAt": "2025-08-11T22:21:56.077Z", "currency": "USD", "fee": null, "feeHash": null, "gasFee": null, "gasPrice": null, "gasUsed": null, "hash": "0x229d811ef34a9f12454e89f12e06945dfc8122538a0af6369ec3f2a2f9aa8cbb", "id": "fe2d8c39-a6ba-41cb-99e7-05c4dcee6c94", "metadata": null, "network": "testnet", "note": null, "rate": null, "rateUSD": "0.00", "reason": "{\"method\":\"transfer\",\"parameters\":[\"0x451dEFC27B45808078e875556AF06bCFdC697BA4\",\"10000\"],\"abi\":{\"constant\":false,\"inputs\":[{\"name\":\"_to\",\"type\":\"address\"},{\"name\":\"_value\",\"type\":\"uint256\"}],\"name\":\"transfer\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"}}", "recipientAddress": "0x036CbD53842c5426634e7929541eC2318f3dCF7e", "reference": "xvLz7CIFoD", "senderAddress": "0x947514e4B803e312C312da0F1B41fEDdbe15ae7a", "signedTransaction": "0xf8ab3e83124fc08301623d94036cbd53842c5426634e7929541ec2318f3dcf7e80b844a9059cbb000000000000000000000000451defc27b45808078e875556af06bcfdc697ba400000000000000000000000000000000000000000000000000000000000027108302948ca0c86783ba50374a959907d9174c2a0b5cd3a87d55336e6c9a6420fde0dd07303ea019a93dad742a9bed4c6d1f514f7fe26777e8f17fe090967a9719afddaa281d64", "status": "SUCCESS", "toAmount": null, "toCurrency": null, "tokenAddress": "0x036CbD53842c5426634e7929541eC2318f3dCF7e", "type": "SIGNED", "updatedAt": "2025-08-11T22:21:56.077Z", "wallet": { "address": "0x947514e4B803e312C312da0F1B41fEDdbe15ae7a", "configurations": null, "createdAt": "2024-08-22T16:05:46.167Z", "derivationPath": "m/44'/60'/0'/0/0", "description": "This is Base wallet", "id": "e17dea25-6c01-4b3a-a4ae-51f411bf69cd", "isActive": true, "name": "Base Wallet", "network": "testnet", "status": "ACTIVE", "updatedAt": "2024-08-22T16:05:46.167Z" } }, "message": "Contract write signed successfully", "statusCode": 200 }

​
Batch Operations

This endpoint supports batch operations, allowing you to sign multiple contract write operations from a specific child address without broadcasting them.

​
Batch Request Format

To sign multiple transactions, use the calls array: 
{
  "calls": [
    {
      "address": "0xTokenContract...",
      "method": "approve",
      "parameters": ["0xSpender...", "1000000000000000000"],
      "abi": [...],
      "reference": "approve-tx"
    },
    {
      "address": "0xProtocolContract...",
      "method": "deposit",
      "parameters": ["1000000000000000000"],
      "abi": [...],
      "reference": "deposit-tx"
    }
  ],
  "code": "123456"
}

​
Batch Response Format

Returns signed transactions without broadcasting: 
{
  "message": "Batch contract write signed successfully",
  "statusCode": 200,
  "data": {
    "success": [
      { "index": 0, "method": "approve", "signedTransaction": "0x..." },
      { "index": 1, "method": "deposit", "signedTransaction": "0x..." }
    ],
    "errors": []
  }
}

​
Validation Rules

RuleValue
Max batch size20 operations
Min batch size1 operation
2FA requiredYes

​
Use Cases

  • Offline signing: Sign transactions for later broadcast
  • Transaction preparation: Prepare multiple transactions in advance
  • Multi-signature workflows: Generate signed payloads for multi-sig wallets

Authorizations

​
x-api-key
string
header
required

Path Parameters

​
walletId
string
required
Example:

"YOUR_WALLET_ID"

​
addressId
string
required
Example:

"ADDRESS_ID"

Body

application/json
​
calls
object[]
Example:
[
  {
    "abi": [
      {
        "constant": false,
        "inputs": [
          { "name": "_to", "type": "address" },
          { "name": "_value", "type": "uint256" }
        ],
        "name": "transfer",
        "outputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
      }
    ],
    "address": "0x337610d27c682E347C9cD60BD4b3b107C9d34dDd",
    "method": "transfer",
    "parameters": [
      "0x2455eC6700092991Ce0782365A89d5Cd89c8Fa22",
      "10000"
    ]
  },
  {
    "abi": [
      {
        "constant": false,
        "inputs": [
          { "name": "_to", "type": "address" },
          { "name": "_value", "type": "uint256" }
        ],
        "name": "transfer",
        "outputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
      }
    ],
    "address": "0x337610d27c682E347C9cD60BD4b3b107C9d34dDd",
    "method": "transfer",
    "parameters": [
      "0x2455eC6700092991Ce0782365A89d5Cd89c8Fa22",
      "10000"
    ]
  }
]

Response

200 - application/json

Ethereum / Tron / Ethereum (Batch) / Tron (Batch)

​
data
object
​
message
string
Example:

"Contract write signed successfully"

​
statusCode
number
Example:

200