# Mobile work-around

To use paymaster transactions on ZKsync, the Viem implementation requires you to `import {eip712WalletActions} from 'viem/zksync'`and extend a `WalletClient` with it.

However, this modifies the `WalletClient.SendTransaction()` function by replacing the `eth_sendTransaction` JSON RPC API method by the `eth_sendRawTransaction` method, which is not supported on several mobile wallets.

The current work-around for making paymaster transactions work with all wallets is to sign the transaction using a `WalletClient`, and then send the signed transaction using a `PublicClient` supporting the eth\_sendRawTransaction. The simplest way is to use a public JSON RPC endpoint, such as <https://mainnet.era.zksync.io>.

#### Classic Paymaster implementation (not compatible with all wallets):

```typescript
  // Paymaster Data received from Zyfi's API
  const pmData = await submitTxDataToAPI(API_URL, dataTxRequest)

  // Extend wallet client to support paymaster transactions
  const wClient = walletClient.extend(eip712WalletActions())

    // Prepare transaction request
    const txReq = await wClient.prepareTransactionRequest({
      account: address,
      to: toAddress,
      value: ETH_AMOUNT,
      chain: zkSync,
      gas: BigInt(pmData.gasLimit),
      gasPerPubdata: BigInt(pmData.txData.customData.gasPerPubdata),
      maxFeePerGas: BigInt(pmData.txData.maxFeePerGas),
      maxPriorityFeePerGas: 0n,
      data: pmData.txData.data,
      paymaster: pmData.txData.customData.paymasterParams.paymaster,
      paymasterInput: pmData.txData.customData.paymasterParams.paymasterInput,
    })

    //  Signs and sends to an endpoint that might be incompatible with eth_sendRawTransaction 
    const hash = await wClient.sendTransaction(txReq)
```

#### Work-around Paymaster Implementation (Works with all wallets)

```typescript
  // Paymaster Data received from Zyfi's API
  const pmData = await submitTxDataToAPI(API_URL, dataTxRequest)

  // Extend wallet client to support paymaster transactions
  const wClient = walletClient.extend(eip712WalletActions())
  
  // Create custom public client with an endpoint that suports eth_sendRawTransaction
  const publicClient = createPublicClient({
    chain: zkSync,
    transport: http('https://mainnet.era.zksync.io')
  })
  
  
  const txReq = await wClient.prepareTransactionRequest({
      account: address,
      to: toAddress,
      value: ETH_AMOUNT,
      chain: zkSync,
      gas: BigInt(pmData.gasLimit),
      gasPerPubdata: BigInt(pmData.txData.customData.gasPerPubdata),
      maxFeePerGas: BigInt(pmData.txData.maxFeePerGas),
      maxPriorityFeePerGas: 0n,
      data: pmData.txData.data,
      paymaster: pmData.txData.customData.paymasterParams.paymaster,
      paymasterInput: pmData.txData.customData.paymasterParams.paymasterInput,
    })
    
    // Sign with Wallet and send signed transaction directly to a compatible endpoint
    const signature = await wClient.signTransaction(txReq)
    const hash = await publicClient.sendRawTransaction({ serializedTransaction: signature })

```

It's a workaround that works perfectly for Dapps wanting to support paymaster functionality on mobile within ZKsync chains.


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