paymasterService

Enable sponsored transactions using ERC-4337 paymaster web services

Defined in ERC-7677

The paymasterService capability enables apps to sponsor user transactions using ERC-4337 paymaster web services. This allows users to execute transactions without paying gas fees directly.

This capability is not yet finalized and may change in future iterations.

Parameters

url · string · required

The URL of the ERC-7677-compliant paymaster service that will sponsor the transactions.

Format: Must be a valid HTTPS URL pointing to a paymaster service endpoint.

Returns

paymasterService · object

The paymaster service capability configuration for the specified chain.

Show PaymasterService capability properties

supported · boolean

Indicates whether the wallet supports paymaster service integration.

Example Usage

Check Paymaster Support

const capabilities = await provider.request({
  method: 'wallet_getCapabilities',
  params: [userAddress]
});

const paymasterSupport = capabilities["0x2105"]?.paymasterService;

Capability Response (Supported)

{
  "0x2105": {
    "paymasterService": {
      "supported": true
    }
  }
}

Error Handling

Code	Message	Description
4100	Paymaster service not supported	Wallet does not support paymaster service integration
4200	Invalid paymaster URL	The provided paymaster service URL is invalid or unreachable
4300	Paymaster service error	The paymaster service returned an error or is unavailable
5700	Paymaster capability required	Transaction requires paymaster service but wallet doesn’t support it

Paymaster Service Implementation

The paymaster service must implement ERC-7677 compliance with these endpoints:

1. Gas Estimation Endpoint

// pm_getPaymasterStubData
POST /rpc
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "pm_getPaymasterStubData",
  "params": [
    userOp, // User operation object
    entryPoint, // Entry point address
    chainId, // Chain ID
    context // Additional context
  ]
}

2. Paymaster Data Endpoint

// pm_getPaymasterData
POST /rpc
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "pm_getPaymasterData", 
  "params": [
    userOp, // User operation object
    entryPoint, // Entry point address
    chainId, // Chain ID
    context // Additional context
  ]
}

Complete Example

Here’s a complete example of implementing sponsored transactions:

class SponsoredTransactionManager {
  private paymasterUrl = "https://api.example.com/paymaster";
  
  async executeSponsored(calls: any[]) {
    try {
      // 1. Check paymaster capability
      const capabilities = await provider.request({
        method: 'wallet_getCapabilities',
        params: [userAddress]
      });
      
      if (!capabilities["0x2105"]?.paymasterService?.supported) {
        throw new Error("Paymaster services not supported");
      }
      
      // 2. Execute sponsored transaction
      const result = await provider.request({
        method: 'wallet_sendCalls',
        params: [{
          version: "1.0",
          chainId: "0x2105",
          from: userAddress,
          calls,
          capabilities: {
            paymasterService: {
              url: this.paymasterUrl
            }
          }
        }]
      });
      
      console.log("Sponsored transaction submitted:", result);
      return result;
      
    } catch (error) {
      console.error("Sponsored transaction failed:", error);
      throw error;
    }
  }
  
  // Example: Sponsored token transfer
  async sponsoredTransfer(token: string, to: string, amount: string) {
    const calls = [{
      to: token,
      value: "0x0",
      data: this.encodeTransfer(to, amount)
    }];
    
    return this.executeSponsored(calls);
  }
  
  private encodeTransfer(to: string, amount: string): string {
    // Encode ERC-20 transfer function call
    // This is a simplified example
    return `0xa9059cbb${to.slice(2).padStart(64, '0')}${BigInt(amount).toString(16).padStart(64, '0')}`;
  }
}

// Usage
const sponsoredTx = new SponsoredTransactionManager();

// Execute sponsored token transfer
await sponsoredTx.sponsoredTransfer(
  "0xA0b86a33E6441b8a2f0d2d2a71Cba0F42c4B1D2E", // USDC token
  "0x742d35Cc4Bf53E0e6C42E5d9F0A8D2F6D8A8B7C9", // recipient
  "1000000" // 1 USDC (6 decimals)
);

Error Handling

Handle paymaster-related errors appropriately:

async function executeWithPaymaster(calls: any[]) {
  try {
    const result = await provider.request({
      method: 'wallet_sendCalls',
      params: [{
        version: "1.0",
        chainId: "0x2105",
        from: userAddress,
        calls,
        capabilities: {
          paymasterService: {
            url: "https://paymaster.example.com"
          }
        }
      }]
    });
    
    return result;
    
  } catch (error) {
    if (error.code === 4100) {
      console.error("Paymaster service not supported");
      // Fallback to regular transaction
      return executeRegularTransaction(calls);
    } else if (error.message.includes("paymaster")) {
      console.error("Paymaster service error:", error);
      // Handle paymaster-specific errors
      throw new Error("Transaction sponsorship failed");
    } else {
      console.error("Transaction failed:", error);
      throw error;
    }
  }
}

Use Cases

Gaming Applications

// Sponsor in-game item purchases
const gameItemPurchase = await provider.request({
  method: 'wallet_sendCalls',
  params: [{
    version: "1.0",
    chainId: "0x2105",
    from: playerAddress,
    calls: [{
      to: gameContractAddress,
      value: "0x0",
      data: purchaseItemCallData
    }],
    capabilities: {
      paymasterService: {
        url: "https://game-paymaster.example.com"
      }
    }
  }]
});

DeFi Onboarding

// Sponsor first-time user transactions
const onboardingTx = await provider.request({
  method: 'wallet_sendCalls',
  params: [{
    version: "1.0", 
    chainId: "0x2105",
    from: newUserAddress,
    calls: [
      // Stake tokens
      {
        to: stakingContract,
        value: "0x0",
        data: stakeCallData
      }
    ],
    capabilities: {
      paymasterService: {
        url: "https://defi-onboarding-paymaster.example.com"
      }
    }
  }]
});

Best Practices

1. Validate Paymaster URLs: Ensure paymaster service URLs are trustworthy and ERC-7677 compliant
2. Handle Failures Gracefully: Implement fallbacks for when paymaster services are unavailable
3. Monitor Costs: Track paymaster usage to manage sponsorship costs
4. User Communication: Clearly communicate when transactions are sponsored

The paymaster service capability enables seamless user experiences by removing the need for users to hold native tokens for gas fees.