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The simplest way to enable ERC-20 gas payments. Gelato’s SDK handles token payment automatically - just specify the payment token and send your UserOperation.

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Installation

npm install @gelatocloud/gasless viem

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Implementation

1

Create an API Key

Check out our How-To Guide for detailed instructions on generating an API key.
2

Create Smart Account

import { createGelatoBundlerClient, token, toGelatoSmartAccount } from '@gelatocloud/gasless';
import { createPublicClient, http, type Hex } from 'viem';
import { privateKeyToAccount } from "viem/accounts";
import { baseSepolia } from "viem/chains";

const owner = privateKeyToAccount(process.env.PRIVATE_KEY as Hex);

const client = createPublicClient({
  chain: baseSepolia,
  transport: http(),
});

const account = await toGelatoSmartAccount({
  client,
  owner,
});
3

Create Bundler Client with Token Payment

Specify the ERC-20 token address using token():
const USDC_ADDRESS = "0x036CbD53842c5426634e7929541eC2318f3dCF7e"; // USDC (Base Sepolia)

const bundler = await createGelatoBundlerClient({
  account,
  apiKey: process.env.GELATO_API_KEY,
  client,
  payment: token(USDC_ADDRESS),
});
4

Send UserOperation

const hash = await bundler.sendUserOperation({
  calls: [
    {
      to: '0xE27C1359cf02B49acC6474311Bd79d1f10b1f8De',
      data: '0xd09de08a', // increment()
    }
  ]
});

console.log(`User operation hash: ${hash}`);

const { receipt } = await bundler.waitForUserOperationReceipt({ hash });
console.log(`Transaction hash: ${receipt.transactionHash}`);

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How It Works

When using direct payment with Gelato:
  1. Fee Calculation - Gelato calculates the gas fee in the specified ERC-20 token
  2. Token Approval - Ensure your smart account has approved Gelato’s paymaster to spend the token
  3. Automatic Deduction - The fee is automatically deducted from your smart account’s token balance
  4. Transaction Execution - Gelato sponsors the native gas and executes your UserOperation
Your smart account must have sufficient ERC-20 token balance to cover the gas fee. Use getUserOperationQuote() to estimate the fee before sending.

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Get Fee Quote

Estimate the fee before sending: 
const quote = await bundler.getUserOperationQuote({
  calls: [
    {
      to: '0xE27C1359cf02B49acC6474311Bd79d1f10b1f8De',
      data: '0xd09de08a',
    }
  ]
});

console.log('Fee:', quote.fee);           // Fee in token units
console.log('Total gas:', quote.gas);     // Total gas
console.log('L1 fee:', quote.l1Fee);      // L1 data fee (L2 chains)

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Additional Resources