The CDP SDK’s sendTransaction method handles gas estimation, nonce management, transaction signing, and broadcasting for EVM accounts. This means that you don’t need to specify these details when you submit a transaction onchain. CDP’s nonce management system ensures that the nonce is set correctly for each transaction, and the gas price is estimated to ensure that the transaction is sent at a reasonable price. You can read more about the sendTransaction API in the API Reference.
The SendTransaction API, which handles both signing and broadcasting, is currently supported only on Base, Ethereum, Avalanche, Polygon, Optimism and Arbitrum.For other networks, use the SignTransaction API for signing and rely on your own RPC URLs to broadcast transactions as shown here.
The following code snippet demonstrates how to send a transaction using the sendTransaction method. You can also refer to our example code in Typescript and Python. 
import dotenv from "dotenv";
import { parseEther, createPublicClient, http } from "viem";
import { baseSepolia } from "viem/chains";

import { CdpClient } from "@coinbase/cdp-sdk";

dotenv.config();

/**
 * This script demonstrates using the new sendTransaction method to:
 * 1. Create a new ethereum account on CDP
 * 2. Request ETH from CDP faucet
 * 3. Sign and send a transaction in a single method call.
 */
async function main() {
  const cdp = new CdpClient();
  const publicClient = createPublicClient({ chain: baseSepolia, transport: http() });

  // Step 1: Create a new EVM account
  const evmAccount = await cdp.evm.createAccount();
  console.log("Successfully created EVM account:", evmAccount.address);

  // Step 2: Request ETH from the faucet
  const faucetResp = await cdp.evm.requestFaucet({
    address: evmAccount.address,
    network: "base-sepolia",
    token: "eth",
  });

  // Wait for the faucet transaction to be confirmed onchain.
  const faucetTxReceipt = await publicClient.waitForTransactionReceipt({
    hash: faucetResp.transactionHash,
  });

  console.log("Successfully requested ETH from faucet:", faucetTxReceipt.transactionHash);

  // Step 3: Sign and send the transaction in a single step with sendTransaction.
  // The API will automatically estimate the gas price and determine the nonce.
  const txResult = await cdp.evm.sendTransaction({
    address: evmAccount.address,
    network: "base-sepolia",
    transaction: {
      to: "0x4252e0c9A3da5A2700e7d91cb50aEf522D0C6Fe8", // recipient address
      value: parseEther("0.000001"), // sending 0.000001 ETH
    },
  });

  console.log("Transaction sent successfully!");
  console.log(
    `Transaction explorer link: https://sepolia.basescan.org/tx/${txResult.transactionHash}`,
  );

  await publicClient.waitForTransactionReceipt({ hash: txResult.transactionHash });

  console.log("Transaction confirmed!");
}

main().catch(console.error);