Mini Apps Wallet Integration

Mini Apps can interact with a user’s EVM wallet without needing to worry about popping open “select your wallet” dialogs or flaky connections.

Getting Started

The Mini App SDK exposes an EIP-1193 Ethereum Provider API at sdk.wallet.getEthereumProvider(). We recommend using Wagmi to connect to and interact with the user’s wallet. This is not required but provides high-level hooks for interacting with the wallet in a type-safe way.

Send a Transaction

You’re now ready to prompt the user to transact. They will be shown a preview of the transaction in their wallet and asked to confirm it: Follow this guide from Wagmi on sending a transaction (note: skip step 1 since you’re already connected to the user’s wallet).

Additional Features

Batch Transactions

The Farcaster Wallet now supports EIP-5792 wallet_sendCalls, allowing you to batch multiple transactions into a single user confirmation. This improves the user experience by enabling operations like “approve and swap” in one step. Common use cases include:

• Approving a token allowance and executing a swap
• Multiple NFT mints in one operation
• Complex DeFi interactions requiring multiple contract calls

Using Batch Transactions

With Wagmi’s useSendCalls hook, sending multiple transactions as a batch is simple:

import { useSendCalls } from 'wagmi'
import { parseEther } from 'viem'

function BatchTransfer() {
  const { sendCalls } = useSendCalls()

return (
    <button
      onClick={() =>
        sendCalls({
          calls: [
            {
              to: '0x70997970C51812dc3A010C7d01b50e0d17dc79C8',
              value: parseEther('0.01')
            },
            {
              to: '0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC',
              value: parseEther('0.02')
            }
          ]
        })
      }
    >
      Send Batch Transfer
    </button>
  )
}

Example: Token Approval and Swap

import { useSendCalls } from 'wagmi'
import { encodeFunctionData, parseUnits } from 'viem'

function ApproveAndSwap() {
  const { sendCalls } = useSendCalls()

const handleApproveAndSwap = () => {
    sendCalls({
      calls: [
        // Approve USDC
        {
          to: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
          data: encodeFunctionData({
            abi: erc20Abi,
            functionName: 'approve',
            args: ['0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D', parseUnits('100', 6)]
          })
        },
        // Swap USDC for ETH
        {
          to: '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D',
          data: encodeFunctionData({
            abi: uniswapAbi,
            functionName: 'swapExactTokensForETH',
            args: [/* swap parameters */]
          })
        }
      ]
    })
  }

return (
    <button onClick={handleApproveAndSwap}>
      Approve & Swap
    </button>
  )
}

All transactions are individually validated and scanned for security, maintaining the same safety guarantees as single transactions.

Limitations:

• Transactions execute sequentially, not atomically
• No paymaster support yet
• Available on all EVM chains Farcaster supports

Use individual transactions when you need to check outputs between calls.

Troubleshooting

Transaction Scanning

Modern crypto wallets scan transactions and preview them to users to help protect users from scams. New contracts and applications can generate false positives in these systems. If your transaction is being reported as potentially malicious use this Blockaid Tool to verify your app with Blockaid.