Using Zerodev Paymaster

This page details the process of sponsoring user operations (UserOps) using Gelato bundler and Zerodev paymaster.

Sponsored payments using Zerodev paymaster are currently restricted to testnets as part of our staging environment. For this functionality, please use staging Gelato Bundler RPC as bundler transport. Checket tesnets listed here.

After Reading this page:

• You'll know how to Sponsor UserOps using Zerodev paymaster.

• You'll learn about how to use Zerodev Kernel and Safe Account with 1Balance.

• You'll see some code which will help you send a Sponsored UserOp within minutes.

Initial Steps

1. Create Your ZeroDev Account

Register on the ZeroDev dashboard to access the tools necessary for managing and sponsoring gas fees in your projects.

2. Create a Project for a Specific Network

After signing in, create a new project and choose the network you plan to operate on (e.g., Ethereum, Polygon). This ensures that all settings and configurations match your target chain.

3. Retrieve the Paymaster URL

Within your project’s dashboard, locate and copy the Paymaster URL. This endpoint is essential for integrating the sponsorship service into your application.

4. Define Gas Policies for Rate Limiting

In the project settings, configure gas policies to establish rate limits for sponsored transactions. These policies help control resource usage, prevent abuse, and maintain efficient operations. For example, you might set daily or monthly request limits to manage overall costs. Checkout more about gas policies here.

Example Code

1. Create an account using createKernelAccount from @zerodev/sdk

const entryPoint = getEntryPoint("0.7");
const kernelVersion = KERNEL_V3_1;

const ecdsaValidator = await signerToEcdsaValidator(publicClient, {
    signer,
    entryPoint,
    kernelVersion,
});

const account = await createKernelAccount(publicClient, {
    plugins: {
      sudo: ecdsaValidator,
    },
    entryPoint,
    kernelVersion
});

2. Create paymaster client using createZeroDevPaymasterClient

const zerodevPaymaster = createZeroDevPaymasterClient({
    chain: baseSepolia,
    transport: http(PAYMASTER_RPC), // from Zerodev Dashboard
});

3. Create an Client using createKernelAccountClient adding Gelato Bundler RPC with Zerodev paymaster

When using the Gelato Bundler with ZeroDev Paymaster, it's essential to use a specialized gas estimation method when creating the kernelClient. This tailored approach ensures that gas calculations are optimized for sponsored transactions with Gelato Bundler.

const gasPrices = await bundlerClient.request<EthGetUserOperationGasPriceRpc>({
            method: "eth_getUserOperationGasPrice",
            params: [],
});
const maxFeePerGas = BigInt(gasPrices.maxFeePerGas),
const maxPriorityFeePerGas = BigInt(gasPrices.maxPriorityFeePerGas),

const kernelClient = createKernelAccountClient({
    account,
    chain: baseSepolia,
    bundlerTransport: http(STAGING_BUNDLER_RPC),
    client: publicClient,
    paymaster: zerodevPaymaster,
    userOperation: {
      estimateFeesPerGas: async ({ bundlerClient }) => {
        const gasPrices =
          await bundlerClient.request<EthGetUserOperationGasPriceRpc>({
            method: "eth_getUserOperationGasPrice",
            params: [],
          });
        return {
          maxFeePerGas: BigInt(gasPrices.maxFeePerGas),
          maxPriorityFeePerGas: BigInt(gasPrices.maxPriorityFeePerGas),
        };
      },
    },
});

Gas Config Types

type GasPrices = {
  maxFeePerGas: string;
  maxPriorityFeePerGas: string;
};

type EthGetUserOperationGasPriceRpc = {
  ReturnType: GasPrices;
  Parameters: [];
};

4. Send UserOperation using kernelClient

console.log("Preparing dummy transaction");
const callData = await kernelClient.account.encodeCalls([
    {
      to: "0x0000000000000000000000000000000000000000",
      value: BigInt(0),
      data: "0x",
    },
  ]);

console.log("Sending user operation...");
const userOpHash = await kernelClient.sendUserOperation({ callData });
console.log("UserOp taskId:", userOpHash);

5. Check UserOp status using Relay API

The userOpHash, when using the Gelato Bundler, is equivalent to the Task ID. This Task ID can be easily debugged through the Relay API, providing a streamlined method for troubleshooting and monitoring the status of transactions. Checkout here.

Explore the complete example code that demonstrates how to sponsor UserOps using Zerodev Paymaster with the ZeroDev Kernel here, as well as how to integrate with a Safe account here.