Sponsor Gas with Gas Tank

Gelato’s Gas Tank is a powerful alternative to traditional onchain paymasters. It acts as a cross-chain gas tank, allowing you to sponsor gas fees across any supported EVM-compatible chain - using just a single balance. Instead of maintaining balances on multiple chains, you only need to deposit funds in one place, and you’re ready to sponsor gas anywhere.

Important: When using Gelato Bundler for Sponsoring Transactions with Gas Tank, both maxFeePerGas and maxPriorityFeePerGas are set to 0. This allows transaction fees to be accurately settled post-execution, rather than upfront via the EntryPoint.

Implementations

Gelato Gasless SDK
Viem
Permissionless
API Endpoints

npm install @gelatocloud/gasless viem

Create an API Key

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

Create Smart Account

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

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

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

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

Create Bundler Client

const bundler = await createGelatoBundlerClient({
  account,
  apiKey: process.env.GELATO_API_KEY,
  client,
  payment: sponsored(),
  pollingInterval: 100
});

Send UserOperation

const hash = await bundler.sendUserOperation({
  calls: [
    {
      data: '0xd09de08a',
      to: '0xE27C1359cf02B49acC6474311Bd79d1f10b1f8De'
    }
  ]
});
console.log(`User operation hash: ${hash}`);

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

npm install viem

Create an API Key

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

Create Bundler Client

Use https://api.gelato.cloud for mainnets, or https://api.t.gelato.cloud for testnets. Pass the API key in the X-API-Key header via fetchOptions.

import { createPublicClient, http } from "viem";
import { createBundlerClient } from "viem/account-abstraction";
import { privateKeyToAccount } from "viem/accounts";
import { baseSepolia } from "viem/chains";

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

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

const bundlerClient = createBundlerClient({
  client: publicClient,
  transport: http(`https://api.gelato.cloud/rpc/84532?payment=sponsored`, {
    fetchOptions: {
      headers: {
        'X-API-Key': process.env.GELATO_API_KEY
      }
    }
  }),
});

Send UserOperation

To use Gas Tank sponsorship efficiently, set maxFeePerGas and maxPriorityFeePerGas to 0n. This allows transaction fees to be settled after execution via Gelato Gas Tank.

const hash = await bundlerClient.sendUserOperation({
  account,
  calls: [
    {
      data: '0xd09de08a',
      to: '0xE27C1359cf02B49acC6474311Bd79d1f10b1f8De',
      value: 0n,
    }
  ],
  maxFeePerGas: 0n,
  maxPriorityFeePerGas: 0n,
});
console.log(`User operation hash: ${hash}`);

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

npm install permissionless viem

Create an API Key

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

Create Smart Account

import { createSmartAccountClient } from "permissionless";
import { createPublicClient, http } from "viem";
import { createBundlerClient, toSoladySmartAccount } from "viem/account-abstraction";
import { privateKeyToAccount } from "viem/accounts";
import { baseSepolia } from "viem/chains";

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

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

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

Create Smart Account Client

Use https://api.gelato.cloud for mainnets, or https://api.t.gelato.cloud for testnets. Pass the API key in the X-API-Key header via fetchOptions.

const smartClient = createSmartAccountClient({
  account,
  chain: baseSepolia,
  bundlerTransport: http(`https://api.gelato.cloud/rpc/84532?payment=sponsored`, {
    fetchOptions: {
      headers: {
        'X-API-Key': process.env.GELATO_API_KEY
      }
    }
  }),
});

Send UserOperation

To use Gas Tank sponsorship efficiently, set maxFeePerGas and maxPriorityFeePerGas to 0n. This allows transaction fees to be settled after execution via Gelato Gas Tank.

const hash = await smartClient.sendUserOperation({
  account,
  calls: [
    {
      data: '0xd09de08a',
      to: '0xE27C1359cf02B49acC6474311Bd79d1f10b1f8De',
      value: 0n,
    }
  ],
  maxFeePerGas: 0n,
  maxPriorityFeePerGas: 0n,
});
console.log(`User operation hash: ${hash}`);

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

Use https://api.gelato.cloud for mainnets, or https://api.t.gelato.cloud for testnets. Pass the API key in the X-API-Key header.

Create an API Key

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

Send UserOperation

To use Gas Tank sponsorship, ensure your UserOperation includes maxFeePerGas and maxPriorityFeePerGas set to "0x0":

{
  "sender": "0x...",
  "nonce": "0x...",
  "callData": "0x...",
  "maxFeePerGas": "0x0",
  "maxPriorityFeePerGas": "0x0",
  ...
}

const response = await fetch(
  `https://api.gelato.cloud/rpc/${chainId}?payment=sponsored`,
  {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-API-Key": process.env.GELATO_API_KEY
    },
    body: JSON.stringify({
      jsonrpc: "2.0",
      method: "eth_sendUserOperation",
      params: [userOperation, entryPoint],
      id: 1,
    }),
  }
);

const data = await response.json();
const userOpHash = data.result;

Estimate Gas (Optional)

const response = await fetch(
  `https://api.gelato.cloud/rpc/${chainId}`,
  {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-API-Key": process.env.GELATO_API_KEY
    },
    body: JSON.stringify({
      jsonrpc: "2.0",
      method: "eth_estimateUserOperationGas",
      params: [userOperation, entryPoint],
      id: 1,
    }),
  }
);

const data = await response.json();
const gasEstimate = data.result;

Get UserOperation Receipt

const response = await fetch(
  `https://api.gelato.cloud/rpc/${chainId}`,
  {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-API-Key": process.env.GELATO_API_KEY
    },
    body: JSON.stringify({
      jsonrpc: "2.0",
      method: "eth_getUserOperationReceipt",
      params: [userOpHash],
      id: 1,
    }),
  }
);

const data = await response.json();
const receipt = data.result;

Available Endpoints

eth_sendUserOperation

Send a user operation to the bundler

eth_estimateUserOperationGas

Estimate gas for a user operation

eth_getUserOperationReceipt

Get receipt for a user operation

eth_getUserOperationByHash

Get user operation by hash

Gelato Paymaster & Bundler

Features

How-To Guides

Gas Tank

Bundler API Endpoints

Additional Resources

Sponsor Gas with Gas Tank

Implementations

Available Endpoints

eth_sendUserOperation

eth_estimateUserOperationGas

eth_getUserOperationReceipt

eth_getUserOperationByHash

Gelato Paymaster & Bundler

Features

How-To Guides

Gas Tank

Bundler API Endpoints

Additional Resources

​Implementations

​Available Endpoints

eth_sendUserOperation

eth_estimateUserOperationGas

eth_getUserOperationReceipt

eth_getUserOperationByHash

Implementations

Available Endpoints