Bridge with ERC-4337

This guide covers prerequisites, how to create an ERC-4337 account, and how to call the bridge with paymaster configuration.

Prerequisites

@tetherto/wdk-wallet-evm-erc-4337 installed alongside @tetherto/wdk-protocol-bridge-usdt0-evm.
Bundler and paymaster endpoints for your chain (example uses Arbitrum public URLs from the API reference).

Create a WalletAccountEvmErc4337 account

You can construct an ERC-4337 signing account using new WalletAccountEvmErc4337(seed, path, config) with chain, provider, bundler, entry point, and paymaster settings:

ERC-4337 account on Arbitrum

import { WalletAccountEvmErc4337 } from '@tetherto/wdk-wallet-evm-erc-4337'

const seedPhrase = 'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about'

const account = new WalletAccountEvmErc4337(seedPhrase, "0'/0/0", {
  chainId: 42161,
  provider: 'https://arb1.arbitrum.io/rpc',
  bundlerUrl: 'https://api.candide.dev/public/v3/arbitrum',
  entryPointAddress: '0x0000000071727De22E5E9d8BAf0edAc6f37da032',
  safeModulesVersion: '0.3.0',
  paymasterUrl: 'https://api.candide.dev/public/v3/arbitrum',
  paymasterAddress: '0x8b1f6cb5d062aa2ce8d581942bbb960420d875ba',
  paymasterToken: { address: '0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9' }
})

You can wrap that account with the new Usdt0ProtocolEvm(account, config?) constructor:

Usdt0ProtocolEvm with ERC-4337 account

import Usdt0ProtocolEvm from '@tetherto/wdk-protocol-bridge-usdt0-evm'

const bridgeProtocol = new Usdt0ProtocolEvm(account, {
  bridgeMaxFee: 1000000000000000n
})

Run a gasless bridge with paymaster options

You can execute bridge() with a second argument that includes paymasterToken (and optional bridgeMaxFee override) as described in the methods table. Approve the source-chain bridge spender first, then call bridge(). Each call returns one hash for the submitted user operation.

Gasless bridge with paymasterToken

const USDT_TOKEN_ADDRESS = '0xdac17f958d2ee523a2206206994597c13d831ec7'
const USDT0_OFT_ADDRESS = process.env.USDT0_OFT_ADDRESS
const amount = 1000000n
const paymasterToken = { address: '0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9' }

await account.approve({
  token: USDT_TOKEN_ADDRESS,
  spender: USDT0_OFT_ADDRESS,
  amount
})

const result = await bridgeProtocol.bridge(
  {
    targetChain: 'polygon',
    recipient: '0x742d35Cc6634C0532925a3b8D4C9db96C4b4d8b6',
    token: USDT_TOKEN_ADDRESS,
    amount,
    oftContractAddress: USDT0_OFT_ADDRESS
  },
  {
    paymasterToken,
    bridgeMaxFee: 1000000000000000n
  }
)

console.log('Bridge hash:', result.hash)
console.log('Total fee:', result.fee)
console.log('Bridge fee:', result.bridgeFee)

The approval and bridge calls are separate user operations. Persist both hashes if your app needs to audit the complete flow.

Paymaster policies, token addresses, and URLs are service-specific. Confirm supported tokens and networks with your bundler or paymaster provider before production use.

Next Steps

Bridge to non-EVM chains in Bridge cross-ecosystem. For failure modes and cleanup, read Handle errors.

Bridge with ERC-4337

Prerequisites

Create a WalletAccountEvmErc4337 account

Run a gasless bridge with paymaster options

Next Steps

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