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Smart Accounts with Universal Bridge

Learn how to leverage EIP7702 smart accounts to batch Universal Bridge transactions for optimal user experience. This approach enables gasless transactions, batched execution, and seamless cross-chain operations.

Smart accounts with EIP7702 allow you to upgrade any EOA (Externally Owned Account) into a smart account without code changes, enabling advanced features like transaction batching and gas sponsorship.

  • Install the SDK

    npm i thirdweb

  • Set up EIP7702 In-App Wallet

    Configure an in-app wallet with EIP7702 execution mode to enable smart account features:

    import { createThirdwebClient } from "thirdweb";
    import { inAppWallet } from "thirdweb/wallets/in-app";
     
    const client = createThirdwebClient({
      clientId: "your_client_id",
    });
     
    // Create in-app wallet with EIP7702 smart account features
    const wallet = inAppWallet({
      executionMode: {
        mode: "EIP7702",
        sponsorGas: true, // Enable gas sponsorship
      },
    });
     
    // Connect the wallet
    const account = await wallet.connect({
      client,
      strategy: "google", // or other auth strategies
    });

  • Prepare Batched Bridge Transactions

    Use Universal Bridge to prepare transactions, then batch them per step (since each step may be on a different chain):

    import { Bridge, NATIVE_TOKEN_ADDRESS, toWei } from "thirdweb";
    import { sendBatchTransaction } from "thirdweb";
     
    const bridgePreparation = await Bridge.Buy.prepare({
      originChainId: 1, // Ethereum
      originTokenAddress: NATIVE_TOKEN_ADDRESS,
      destinationChainId: 137, // Polygon
      destinationTokenAddress: NATIVE_TOKEN_ADDRESS,
      amount: toWei("0.1"), // 0.1 MATIC
      sender: account.address,
      receiver: account.address,
      client,
    });

  • Execute Batched Transactions

    Execute transactions in batches per step (same chain), proceeding through steps sequentially:

    import { sendBatchTransaction, waitForReceipt } from "thirdweb";
    // Execute each step's transactions as a batch (same chain)
    for (let i = 0; i < bridgePreparation.steps.length; i++) {
      const step = bridgePreparation.steps[i];
     
      // Batch all transactions within this step (they're all on the same chain)
      const stepBatchResult = await sendBatchTransaction({
        transactions: step.transactions,
        account,
      });
     
      console.log(
        `Step ${i + 1} batch sent:`,
        stepBatchResult.transactionHash,
      );
     
      const receipt = await waitForReceipt({
        client,
        chain: step.transactions[0].chain,
        transactionHash: stepBatchResult.transactionHash,
      });
     
      console.log(`Step ${i + 1} completed:`, receipt.status);
     
      // Monitor bridge completion status for this step
      let bridgeStatus;
      do {
        bridgeStatus = await Bridge.status({
          transactionHash: stepBatchResult.transactionHash,
          chainId: step.transactions[0].chainId,
          client,
        });
     
        if (bridgeStatus.status === "PENDING") {
          console.log(`Bridge step ${i + 1} still pending...`);
          await new Promise((resolve) => setTimeout(resolve, 5000));
        }
      } while (bridgeStatus.status === "PENDING");
     
      if (bridgeStatus.status === "COMPLETED") {
        console.log(`Bridge step ${i + 1} completed!`);
      } else if (bridgeStatus.status === "FAILED") {
        throw new Error(`Bridge step ${i + 1} failed`);
      }
    }

Next Steps