Self Hosted Sponsorships

The self-hosted sponsorship feature allows you to operate your own backend service to sponsor gas fees on multiple chains. This is ideal for teams that want full control over sponsorship logic, authentication, and rate limits.

We’ve provided a ready-to-use starter kit to help you get started:

🤔 Why Use Self-Hosted Sponsorship?

Self-hosting gives you:

• Programmable Control: Define custom logic to determine when, and under what conditions users are eligible for gas sponsorship.
• Full Key Ownership: Manage your own private keys for gas tanks and service accounts.
• On-Premise Hosting: Deploy the sponsorship backend in your own secure environment—no dependency on third-party infrastructure.

This is particularly useful for enterprise use cases, partner platforms, or gated dApps requiring more than a one-size-fits-all sponsorship logic.

🏗️ Architecture Overview

There are two main components where you'll use the AbstractJS SDK:

1. Frontend/App Integration – Use the SDK within your application to connect to your sponsorship backend when sending supertransactions.
2. Backend Implementation – Use the SDK in your self-hosted backend to manage gas tank accounts, check balances, deploy contracts, and fulfill sponsorship logic.

🎒 Sponsorship Backend API Reference

In order for MEE sponsorships to work, your backend should expose the following HTTP endpoints:

GET /v1/sponsorship/info

Returns available gas tanks and their balances.

GET /v1/sponsorship/nonce/:chainId/:gasTankAddress

Returns the current nonce and nonce key for a given gas tank.

GET /v1/sponsorship/receipt/:chainId/:hash

Returns the transaction receipt for a sponsorship transaction.

POST /v1/sponsorship/sign/:chainId/:gasTankAddress

Signs a sponsorship quote using a specific gas tank account.

• Body: GetQuotePayload as defined in AbstractJS.
• Perform project-specific logic here (e.g., rate limits, auth).

⌨️ Using Self-Hosted Sponsorship in AbstractJS

To integrate your own backend, pass sponsorshipOptions when calling getFusionQuote. Your backend should expose a compatible API to fetch sponsorship data.

⚙️ Configuration

• url: URL of your sponsorship backend
• customHeaders: Optional custom headers (e.g. for authentication)
• gasTank: Configuration for the gas tank account

💡 Example

const meeClient = await createMeeClient({
  account: mcNexus,
  apiKey: "YOUR_MEE_API_KEY"
})
 
const quote = await meeClient.getFusionQuote({
  trigger: {
    tokenAddress: testnetMcUSDC.addressOn(baseSepolia.id),
    chainId: baseSepolia.id,
    amount: 1n
  },
  sponsorship: true,
  sponsorshipOptions: {
    url: "https://your-backend.com/sponsorship",
    customHeaders: {
      sponsorshipApiKey: "your-api-key",
      otherHeader: "custom-value"
    },
    gasTank: {
      address: "0xC2461985dE59CcA97eBAcBBF1eDBe904ea859c84",
      token: "0x036cbd53842c5426634e7929541ec2318f3dcf7e",
      chainId: baseSepolia.id
    }
  },
  instructions: [
    {
      calls: [
        {
          to: eoaAccount.address,
          value: 1n
        }
      ],
      chainId: baseSepolia.id
    }
  ]
})
 
const { hash } = await meeClient.executeFusionQuote({ fusionQuote: quote })
const { transactionStatus } = await meeClient.waitForSupertransactionReceipt({ hash })

⛽️ Utilities for Sponsorship Gas Tanks

The following utility functions are primarily intended for backend developers managing a gas tank account.

Create a Gas Tank Account

const gasTankAccount = await toGasTankAccount({
  transport: http(), // Use a paid RPC in production
  chain: baseSepolia,
  privateKey: "YOUR_PRIVATE_KEY",
  options: {
    mee: {
      apiKey: "mee_3ZLvzYAmZa89WLGa3gmMH8JJ"
    }
  }
})

Get Gas Tank Address

const { address: gasTankAddress } = await gasTankAccount.getAddress()

Get Gas Tank Balance

const { balance, decimals } = await gasTankAccount.getBalance({
  tokenAddress: testnetMcUSDC.addressOn(baseSepolia.id)
})

Check Deployment Status

const isDeployed = await gasTankAccount.isDeployed()

Deploy and Fund Gas Tank

const { isDeployed, address } = await gasTankAccount.deploy({
  tokenAddress: testnetMcUSDC.addressOn(chain.id),
  amount: parseUnits("0.1", 6)
})

Withdraw Funds

await gasTankAccount.withdraw({
  tokenAddress: testnetMcUSDC.addressOn(baseSepolia.id),
  recipient: eoaAccount.address,
  amount: runtimeERC20BalanceOf({
    targetAddress: gasTankAddress,
    tokenAddress: testnetMcUSDC.addressOn(baseSepolia.id)
  }),
  confirmations: 3
})