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Get Started: Gasless (3rd-party Wallets)

Estimated time to read: 3 minutes

Integrate Web3 apps with Arcana Gasless (Standalone) SDK and enable third-party browser-based wallet users to sign blockchain transactions with zero gas fees.

Only for Third-party Wallets

The Arcana Gasless (Standalone) SDK is not meant to enable gasless transactions via the Arcana wallet.

To enable gasless transactions via the in-app Arcana wallet, integrate the app with the Arcana Auth SDK and use the built-in gasless feature. See Gasless Quick Start Guide for details.

Prerequisites

1. Configure Gasless

Configure gasless transactions for the registered app through the Arcana Developer Dashboard. Set up gas tanks for one or more supported chains. Fund gas tanks, and provide smart contract ABI details to whitelist selected app operations.

Gasless Transaction Limitations

  • Gasless transactions are available only for ERC-20 tokens.
  • To ensure smooth gasless operations, the gas tank must have at least a 0.1 ETH (or native chain token) balance.

2. Install SDK

npm i @arcana/scw

yarn add @arcana/scw

<script src="https://cdn.jsdelivr.net/npm/@arcana/scw"></script>
<script src="https://unpkg.com/@arcana/scw"></script>

3. Integrate App

import { scw } from @arcana/scw;

const scw = new arcana.scw.SCW();
await scw.init("<app_id>", window.ethereum);

The init method is used to initialize the Arcana Gasless (Standalone) SDK with the unique app identifier obtained via the Arcana Developer Dashboard after registering the app. After init you can call other methods of the scw object.

During initialization, an SCW account is associated with the EoA account. All gasless transactions must use this SCW account address.

Use the getSCWAddress to get the logged-in user's smart contract address (SCW Address). Call getPaymasterBalance to check if the gas tank is adequately funded.

  const erc20abi = [...];
  let amount = 0.1;

  const erc20Address = "0x2d7aC0907961c7.......45f981Ed8373b5dF86";
  const toAddress = "0x723455665060698....87689dA78E25";
  const Erc20Interface = new ethers.utils.Interface(erc20abi);

  const encodedData = Erc20Interface.encodeFunctionData("transfer", [
    toAddress,
    ethers.utils.parseEther(amount + ""),
  ]);

  console.log("Address: " + scw.getSCWAddress());

  // Check balance

  console.log("Paymaster Balance: " + (await scw.getPaymasterBalance()) / 1e18);

4. Use DoTx()

Enable gasless transactions for third-party wallets by calling the doTx() method of the Arcana Gasless (Standalone) SDK in the authenticated user's context.

Before calling DoTx()

The Web3 app must be connected with third-party wallets before initiating `DoTx() in the authenticated user's context.

  const erc20abi = [...];
  let amount = 0.1;

  const erc20Address = "0x2d7aC0907961c7.......45f981Ed8373b5dF86";
  const toAddress = "0x723455665060698....87689dA78E25";
  const Erc20Interface = new ethers.utils.Interface(erc20abi);

  const encodedData = Erc20Interface.encodeFunctionData("transfer", [
    toAddress,
    ethers.utils.parseEther(amount + ""),
  ]);

  // You need to create transaction objects of the following interface
  const tx1 = {
    from: scw.getSCWAddress(),
    to: erc20Address, // destination smart contract address
    data: encodedData,
  };

  // Check balance
  // Use scw.getPaymaster() to check whether gas tanks are adequately funded

  console.log("Paymaster Balance: " + (await scw.getPaymasterBalance()) / 1e18);
  if (await scw.getPaymasterBalance()/1e18) > 0 {
    let tx = await scw.doTx(tx1);
    await tx.wait();
    console.log(`Transfer done ${tx.userOpHash}`)
  } else {
    console.log("Insufficient funds in the gas tank.")
  }

That's all!

The 'Gasless' app is ready to onboard users and allow them to sign blockchain transactions.

See Also

'Gasless' integration example: See sample-gasless-metamask-only submodule in Auth Examples

Arcana Gasless (Standalone) SDK Quick Links

Last update: November 4, 2024 by shaloo, shaloo