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Pay Gas for Users

Demo​

Introduction​

By default, your users pay for their own gas, but you can choose to sponsor some (or all) transactions for your users.

Since it's unsafe to sponsor all transactions (in which case your users could drain your funds), you need to configure gas policies to determine which transactions to sponsor.

Go to the Gas Policies section of your dashboard. There are two ways to specify gas policies: global policies and contract policies.

Global Policies​

With global policies, you set general rules such as "I want to sponsor up to 10 transactions per hour per user." You do that under the "Global Policies" section.

For most projects, this is all you need! If you want more fine-grained control, read on for how to set up contract policies.

Contract Policies​

With contract policies, you can specify specific contracts (and functions on the contract) that you want your users to be able to interact with without paying gas. You do that by creating a "Known Contract," then create a "Contract Policy" for the known contract.

Create a known contract​

Create a new known contract by clicking the "New" button in the "Known Contracts" section, then enter:

  • The name of the contract (it can be any name you want; the name is only for identification purposes)
  • The address of the contract.
  • The ABI of the contract.

There are many ways to obtain the ABI of a contract. If you are unsure how to obtain the ABI of your contracts, ask your developers. A valid ABI should be an array like this:

[{
      "inputs": [
        {
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "claim",
      "outputs": [],
      "stateMutability": "nonpayable",
      "type": "function"
}]

Your input should look something like this:

If you plan on sponsor all functions on the contract, you may also input an empty array [].

Now click Create Contract.

Create a new policy​

You configure which transactions to sponsor by setting up policies.

Click New in the "Policies" section and set up the following parameters.

Strategy​

Broadly speaking, there are two types of strategies:

  • Pay gas for users. Here you pay gas for your users either fully or partially.

  • Charge gas in custom tokens. Here your users pay gas, but instead of paying in ETH (or whatever the native gas token is), they pay in a custom ERC20 token, such as the token from your application/protocol.

For this tutorial, choose the Pay gas for users strategy from the dropdown.

Transactions​

Now is the time to specify the transactions for whom you'd like to sponsor gas.

Click + under Allowed Transactions. Select the function you'd like to sponsor, or select the wildcard function * to sponsor every function.

Rate Limits​

To prevent malicious users from abusing the system, it's important to set up rate limits to limit the amount of transactions you sponsor. To create a new rate limit, click + under Rate Limits. You can set up as many rate limits as you want.

At this point, your input should look something like this:

Click Create Policy to finish the setup.

How do I pay for gas?​

Ordinarily with ERC-4337, you would have to set up your own "paymasters," which are on-chain smart contracts that pay gas for users.

With ZeroDev, we simplify the task for you -- you just have to put down a credit card, and we will charge you for gas at the end of every month.

You can set up billing on the dashboard.