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

# createUniversalTransaction()

> Send arbitrary contract interactions, including payable transactions, from a Universal Account.

The **Universal Accounts SDK** supports sending contract interactions, including payable transactions, through the `createUniversalTransaction()` method. In this example, we interact with a smart contract on the **Base Mainnet** that requires exactly 0.0000001 ETH to execute a `checkIn()` function.

By specifying an `expectTokens` array, the SDK ensures the account has the necessary **ETH** on Base—even if the user's assets are on other chains or in different tokens (e.g., USDC, USDT). The SDK will handle all additional required cross-chain routing and token conversion under the hood.

Once the transaction is created, it will return a `rootHash` value representing the payload to be signed. You can then use a signer (e.g., Particle Auth) to sign this hash and broadcast it using `sendTransaction()`.

The following code snippet shows how to use the **Universal Accounts SDK** to send a payable transaction:

```tsx theme={null}
import { CHAIN_ID, SUPPORTED_TOKEN_TYPE } from "@particle-network/universal-account-sdk";
import { Interface, parseEther, toBeHex } from "ethers";
import { useEthereum } from "@particle-network/authkit";

// Extract the provider from Particle Auth
const { provider } = useEthereum();

const contractAddress = "0x14dcD77D7C9DA51b83c9F0383a995c40432a4578";
const interf = new Interface(["function checkIn() public payable"]);

const transaction = await ua.createUniversalTransaction({
  chainId: CHAIN_ID.BASE_MAINNET,
  expectTokens: [
    {
      type: SUPPORTED_TOKEN_TYPE.ETH,
      amount: "0.0000001",
    },
  ],
  transactions: [
    {
      to: contractAddress,
      data: interf.encodeFunctionData("checkIn"),
      value: toBeHex(parseEther("0.0000001")),
    },
  ],
});

const signature = await provider.signMessage(transaction.rootHash);
const result = await ua.sendTransaction(transaction, signature);

console.log("Explorer URL:", `https://universalx.app/activity/details?id=${result.transactionId}`);
```

The returned `TransactionResult` will include the transaction's ID and metadata like token movements and fee breakdowns.

## Next steps

<CardGroup cols="2">
  <Card title="Transaction Preview" icon="eye" href="/universal-accounts/ua-reference/web/transactions/preview">
    Inspect fees and token movements before signing.
  </Card>

  <Card title="sendTransaction() Response" icon="receipt" href="/universal-accounts/ua-reference/web/transactions/send-response">
    Full breakdown of the `TransactionResult` object.
  </Card>
</CardGroup>