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

# How to Create Web3 Transactions in MPC Wallets

<Note>This content applies to WaaS 1.0 only. We highly recommend that you upgrade to [WaaS 2.0](https://www.cobo.com/developers/v2/guides/overview/introduction).</Note>

## Overview

Web3 transactions typically involve interacting with smart contracts on the blockchain, with applications extending to decentralized applications (dApps), non-fungible tokens (NFTs), and beyond. This guide will outline how developers can create Web3 transactions in MPC Wallets using the APIs provided by Cobo.

Note: The code samples below are only applicable to Web3 Wallets under the MPC Wallets.

## Code Samples

#### Initiating a withdraw transaction using Web3 Wallets (e.g., sending 0.01 ETH)

Step 1: Initialize the mpc\_client

Step 2: Create the withdraw transaction

<CodeGroup>
  ```python Python theme={null}
  from cobo_custody.client.mpc_client import MPCClient
  from cobo_custody.config import DEVELOP_ENV
  from cobo_custody.signer.local_signer import LocalSigner
  import time

  api_secret = "your api secret"  # your wallet api secret
  chain_code = "ETH"  # your target chain
  coin_code = "ETH"  # your target coin
  amount = "100000000000000000"  # withdraw amount：0.01ETH
  from_address = "your mpc wallet address"  # your mpc wallet address
  to_address = "to address"  # to address

  # init cobo client
  mpc_client = MPCClient(signer=LocalSigner(api_secret), env=DEVELOP_ENV, debug=False)

  request_id = f"MPCTransaction-{int(time.time() * 1000)}" # your custom request_id
  # create withdraw transaction
  response = mpc_client.create_transaction(
     coin=coin_code,
     request_id=request_id,
     amount=amount,
     from_addr=from_address,
     to_addr=to_address,
     gas_price=6500000000,
     gas_limit=21000,
  )
  print(f"Withdraw: {response.result}")
  ```

  ```java Java theme={null}
  package com.cobo.custody.api.client.impl;

  import java.math.BigDecimal;
  import java.math.BigInteger;

  import com.cobo.custody.api.client.CoboApiClientFactory;
  import com.cobo.custody.api.client.CoboMPCApiRestClient;
  import com.cobo.custody.api.client.config.Env;
  import com.cobo.custody.api.client.domain.ApiResponse;
  import com.cobo.custody.api.client.domain.transaction.MPCPostTransaction;

  public class CobоCustodyApiClientExample {
      public static void main(String[] args) {
          String apiSecret = "your_api_secret"; // your wallet api secret

          // init client
          CoboMPCApiRestClient mpcClient = CoboApiClientFactory.newInstance(
                  new LocalSigner(apiSecret),
                  Env.DEV,
                  false).newMPCRestClient();

          // create withdraw transaction
          String coin = "GETH";
          String requestId = String.valueOf(System.currentTimeMillis());
          String fromAddr = "your mpc wallet address";
          String toAddr = "to address";
          BigInteger amount = new BigInteger("100000000000000000");
          String toAddressDetails = null;
          BigDecimal fee = null;
          BigInteger gasPrice = new BigInteger("6500000000");
          BigInteger gasLimit = new BigInteger("21000");
          Integer operation = null;
          String extraParameters = null;
          ApiResponse<MPCPostTransaction> res = mpcClient.createTransaction(coin, requestId, amount, fromAddr, toAddr,
                  toAddressDetails, fee, gasPrice, gasLimit, operation, extraParameters, null, null, null, null);
          System.out.println("Withdraw: " + res.getResult());
      }
  }
  ```
</CodeGroup>

<br />

#### Interacting with a smart contract using Web3 Wallets

Step 1: Initialize the mpc\_client

Step 2: Pass in calldata to call a smart contract

<CodeGroup>
  ```python Python theme={null}
  from cobo_custody.client.mpc_client import MPCClient
  from cobo_custody.config import DEVELOP_ENV
  from cobo_custody.signer.local_signer import LocalSigner
  import time

  api_secret = "your api secret"  # your wallet api secret
  chain_code = "ETH"  # your target chain
  coin_code = "ETH"  # your target coin
  amount = "0"
  from_address = "your mpc wallet address"  # your mpc wallet address
  to_address = "contract address"  # contract address
  extra_parameters = '{"calldata": "0xa8059cbb000000000000000000000000971948873f869e4517311b190d7eb31e30eba0ef000000000000000000000000000000000000000000000000002386f26fc10000"}' # use calldata to call or deploy contract

  # init cobo client
  mpc_client = MPCClient(signer=LocalSigner(api_secret), env=DEVELOP_ENV, debug=False)

  request_id = f"MPCTransaction-{int(time.time() * 1000)}" # your custom request_id

  response = mpc_client.create_transaction(
     coin=coin_code,
     request_id=request_id,
     amount=amount,
     from_addr=from_address,
     to_addr=to_address,
     gas_price=6500000000,
     gas_limit=22385,
     extra_parameters=extra_parameters,
  )
  print(f"call contract: {response.result}")
  ```

  ```java Java theme={null}
  package com.cobo.custody.api.client.impl;

  import java.math.BigDecimal;
  import java.math.BigInteger;

  import com.cobo.custody.api.client.CoboApiClientFactory;
  import com.cobo.custody.api.client.CoboMPCApiRestClient;
  import com.cobo.custody.api.client.config.Env;
  import com.cobo.custody.api.client.domain.ApiResponse;
  import com.cobo.custody.api.client.domain.transaction.MPCPostTransaction;

  public class CobоCustodyApiClientExample {
      public static void main(String[] args) {
          String apiSecret = "your_api_secret"; // your wallet api secret

          // init client
          CoboMPCApiRestClient mpcClient = CoboApiClientFactory.newInstance(
                  new LocalSigner(apiSecret),
                  Env.DEV,
                  false).newMPCRestClient();

          // create withdraw transaction
          String coin = "GETH";
          String requestId = String.valueOf(System.currentTimeMillis());
          String fromAddr = "your mpc wallet address";
          String toAddr = "contract address";
          BigInteger amount = new BigInteger("0");
          String toAddressDetails = null;
          BigDecimal fee = null;
          BigInteger gasPrice = new BigInteger("6500000000");
          BigInteger gasLimit = new BigInteger("22385");
          Integer operation = null;
          String extraParameters = "{\"calldata\": \"0xa8059cbb000000000000000000000000971948873f869e4517311b190d7eb31e30eba0ef000000000000000000000000000000000000000000000000002386f26fc10000\"}"

          ApiResponse<MPCPostTransaction> res = mpcClient.createTransaction(coin, requestId, amount, fromAddr, toAddr,
                  toAddressDetails, fee, gasPrice, gasLimit, operation, extraParameters, null, null, null, null);
          System.out.println("call contract: " + res.getResult());
      }
  }
  ```
</CodeGroup>

<br />

For more information on the 'create\_transaction' endpoint, please [click here](/v1/api-references/mpc-wallet/mpc_create_transaction).