Sign Transaction

Sign Solana transactions without broadcasting them to the network. This is useful for advanced use cases like off-chain transaction batching, meta-transactions, or custom transaction submission workflows.

Overview

Signing transactions without sending allows you to:

Batch transactions: Collect multiple signed transactions before submitting
Off-chain processing: Sign now, broadcast later
Custom submission: Use custom RPC logic or transaction relayers
Transaction inspection: Review signed transaction data before broadcasting

Unlike sendTransaction which signs and broadcasts immediately, signTransaction only signs the transaction and returns it for you to broadcast separately.

Signing vs Sending

Feature	Sign Transaction	Send Transaction
Signs transaction	✅	✅
Broadcasts to network	❌	✅
Returns	Signed transaction bytes	Transaction signature
Use case	Advanced workflows	Standard transfers

React SDK

Basic Usage
With UI Customization
With Callbacks

To sign a transaction, use the signTransaction method from the useSignTransaction hook:

import { useMoonKey } from '@moon-key/react-auth';
import { useSignTransaction } from '@moon-key/react-auth/solana';
import {
  Transaction,
  SystemProgram,
  PublicKey,
  Connection,
  LAMPORTS_PER_SOL
} from '@solana/web3.js';

function SignTransactionButton() {
  const { user } = useMoonKey();
  const { signTransaction } = useSignTransaction();

  const handleSign = async () => {
    if (!user?.wallet) {
      alert('No wallet found');
      return;
    }

    try {
      const connection = new Connection('https://api.devnet.solana.com');

      // Create transaction
      const transaction = new Transaction().add(
        SystemProgram.transfer({
          fromPubkey: new PublicKey(user.wallet.address),
          toPubkey: new PublicKey('RecipientAddressHere...'),
          lamports: 0.001 * LAMPORTS_PER_SOL
        })
      );

      // Get recent blockhash
      const { blockhash } = await connection.getLatestBlockhash();
      transaction.recentBlockhash = blockhash;
      transaction.feePayer = new PublicKey(user.wallet.address);

      // Sign transaction (does not broadcast)
      const { signedTransaction } = await signTransaction({
        transaction
      });

      console.log('Transaction signed:', signedTransaction);
      alert('Transaction signed successfully!');

      // You can now broadcast it later or store it
    } catch (error) {
      console.error('Failed to sign transaction:', error);
    }
  };

  return (
    <button onClick={handleSign}>
      Sign Transaction
    </button>
  );
}

Parameters

transaction

Transaction | VersionedTransaction

required

The Solana transaction to sign. Can be either a legacy Transaction or VersionedTransaction from @solana/web3.js.Example:

const transaction = new Transaction().add(
  SystemProgram.transfer({
    fromPubkey: new PublicKey(fromAddress),
    toPubkey: new PublicKey(toAddress),
    lamports: amount
  })
);

Options Object

The second parameter is an optional configuration object:

uiConfig

object

Configuration for the signing confirmation modal.

Show uiConfig properties

title

string

Custom title for the confirmation modal.

description

string

Description text shown in the modal.

confirmButtonText

string

Text for the confirm button.

cancelButtonText

string

Text for the cancel button.

transactionInfo

object

Additional transaction information to display.

Show transactionInfo properties

action

string

Description of the action being performed.

cost

string

Estimated cost of the transaction.

showWalletUI

boolean

Whether to show the confirmation modal. Set to false to sign without confirmation.

Hook Callbacks

onSuccess

(result: { signedTransaction: Uint8Array }) => void

Callback executed after successful signing. Receives the signed transaction as Uint8Array.

onError

(error: Error) => void

Callback executed if signing fails or user cancels.

Returns

signedTransaction

Uint8Array

The signed transaction as a Uint8Array. This can be serialized and broadcast to the network.

Complete Examples

Sign and Broadcast Later

'use client';
import { useMoonKey } from '@moon-key/react-auth';
import { useSignTransaction } from '@moon-key/react-auth/solana';
import {
  Transaction,
  SystemProgram,
  PublicKey,
  Connection,
  LAMPORTS_PER_SOL
} from '@solana/web3.js';
import { useState } from 'react';

export default function SignAndBroadcastLater() {
  const { user } = useMoonKey();
  const { signTransaction } = useSignTransaction();
  const [signedTx, setSignedTx] = useState<Uint8Array | null>(null);

  const handleSign = async () => {
    if (!user?.wallet) return;

    const connection = new Connection('https://api.devnet.solana.com');

    const transaction = new Transaction().add(
      SystemProgram.transfer({
        fromPubkey: new PublicKey(user.wallet.address),
        toPubkey: new PublicKey('RecipientAddressHere...'),
        lamports: 0.001 * LAMPORTS_PER_SOL
      })
    );

    const { blockhash } = await connection.getLatestBlockhash();
    transaction.recentBlockhash = blockhash;
    transaction.feePayer = new PublicKey(user.wallet.address);

    try {
      const { signedTransaction } = await signTransaction({
        transaction
      }, {
        uiConfig: {
          title: 'Sign Transaction',
          description: 'Sign transaction to broadcast later',
          confirmButtonText: 'Sign'
        }
      });

      setSignedTx(signedTransaction);
      alert('Transaction signed! Ready to broadcast.');
    } catch (error) {
      console.error('Signing failed:', error);
    }
  };

  const handleBroadcast = async () => {
    if (!signedTx) return;

    try {
      const connection = new Connection('https://api.devnet.solana.com');

      // Deserialize and send the signed transaction
      const transaction = Transaction.from(signedTx);
      const signature = await connection.sendRawTransaction(signedTx);

      console.log('Transaction broadcast:', signature);
      
      // Wait for confirmation
      await connection.confirmTransaction(signature, 'confirmed');
      
      alert(`Transaction confirmed! Signature: ${signature}`);
      setSignedTx(null);
    } catch (error) {
      console.error('Broadcast failed:', error);
      alert('Failed to broadcast transaction');
    }
  };

  return (
    <div className="sign-and-broadcast">
      <h2>Sign Now, Broadcast Later</h2>

      <button onClick={handleSign} disabled={signedTx !== null}>
        Sign Transaction
      </button>

      {signedTx && (
        <div className="signed-tx-actions">
          <p>✅ Transaction signed and ready</p>
          <button onClick={handleBroadcast}>
            Broadcast Transaction
          </button>
        </div>
      )}
    </div>
  );
}

Batch Transaction Signing

'use client';
import { useMoonKey } from '@moon-key/react-auth';
import { useSignTransaction } from '@moon-key/react-auth/solana';
import {
  Transaction,
  SystemProgram,
  PublicKey,
  Connection,
  LAMPORTS_PER_SOL
} from '@solana/web3.js';
import { useState } from 'react';

export default function BatchTransactionSigning() {
  const { user } = useMoonKey();
  const { signTransaction } = useSignTransaction();
  const [signedTxs, setSignedTxs] = useState<Uint8Array[]>([]);

  const handleSignBatch = async () => {
    if (!user?.wallet) return;

    const connection = new Connection('https://api.devnet.solana.com');
    const { blockhash } = await connection.getLatestBlockhash();

    // Create multiple transactions
    const recipients = [
      'Recipient1AddressHere...',
      'Recipient2AddressHere...',
      'Recipient3AddressHere...'
    ];

    const signed: Uint8Array[] = [];

    try {
      for (const recipient of recipients) {
        const transaction = new Transaction().add(
          SystemProgram.transfer({
            fromPubkey: new PublicKey(user.wallet.address),
            toPubkey: new PublicKey(recipient),
            lamports: 0.001 * LAMPORTS_PER_SOL
          })
        );

        transaction.recentBlockhash = blockhash;
        transaction.feePayer = new PublicKey(user.wallet.address);

        const { signedTransaction } = await signTransaction({
          transaction
        }, {
          uiConfig: {
            title: `Sign Transaction ${signed.length + 1}/${recipients.length}`,
            description: `Signing batch transaction ${signed.length + 1} of ${recipients.length}`,
            confirmButtonText: 'Sign'
          }
        });

        signed.push(signedTransaction);
      }

      setSignedTxs(signed);
      alert(`All ${signed.length} transactions signed!`);
    } catch (error) {
      console.error('Batch signing failed:', error);
      alert('Failed to sign all transactions');
    }
  };

  const handleBroadcastBatch = async () => {
    if (signedTxs.length === 0) return;

    const connection = new Connection('https://api.devnet.solana.com');
    const signatures: string[] = [];

    try {
      for (const signedTx of signedTxs) {
        const signature = await connection.sendRawTransaction(signedTx);
        signatures.push(signature);
        console.log('Transaction sent:', signature);
      }

      alert(`All ${signatures.length} transactions broadcast!`);
      setSignedTxs([]);
    } catch (error) {
      console.error('Batch broadcast failed:', error);
    }
  };

  return (
    <div className="batch-signing">
      <h2>Batch Transaction Signing</h2>

      <button onClick={handleSignBatch} disabled={signedTxs.length > 0}>
        Sign Batch Transactions
      </button>

      {signedTxs.length > 0 && (
        <div className="batch-status">
          <p>✅ {signedTxs.length} transactions signed</p>
          <button onClick={handleBroadcastBatch}>
            Broadcast All
          </button>
        </div>
      )}
    </div>
  );
}

Broadcasting Signed Transactions

After signing a transaction, you can broadcast it using Solana’s connection:

import { Connection } from '@solana/web3.js';

// Broadcast signed transaction
const connection = new Connection('https://api.devnet.solana.com');
const signature = await connection.sendRawTransaction(signedTransaction);

console.log('Transaction signature:', signature);

// Wait for confirmation
const confirmation = await connection.confirmTransaction(signature, 'confirmed');

if (confirmation.value.err) {
  console.error('Transaction failed');
} else {
  console.log('Transaction confirmed!');
}

With Custom Commitment

// Use different commitment levels
await connection.confirmTransaction(signature, 'processed'); // Fast, less secure
await connection.confirmTransaction(signature, 'confirmed'); // Balanced
await connection.confirmTransaction(signature, 'finalized'); // Slow, most secure

Transaction Serialization

Serialize to Base64

import { Transaction } from '@solana/web3.js';

// Convert signed transaction to base64
const transaction = Transaction.from(signedTransaction);
const base64Tx = Buffer.from(signedTransaction).toString('base64');

console.log('Base64 transaction:', base64Tx);

Deserialize from Base64

// Convert base64 back to transaction
const txBuffer = Buffer.from(base64Tx, 'base64');
const transaction = Transaction.from(txBuffer);

UI Customization

Customize the signing modal:

await signTransaction({
  transaction
}, {
  uiConfig: {
    title: 'Sign Transaction',
    description: 'Review and sign this transaction',
    confirmButtonText: 'Sign',
    cancelButtonText: 'Cancel',
    transactionInfo: {
      action: 'Transfer SOL',
      cost: '0.001 SOL'
    }
  }
});

await signTransaction({
  transaction
}, {
  uiConfig: {
    showWalletUI: false
  }
});

Hiding the modal removes the user’s ability to review the transaction before signing. Only use this for trusted operations or after obtaining explicit user consent.

Best Practices

Use fresh blockhashes

Always fetch a recent blockhash before signing:

// ✅ Good - Fresh blockhash
const { blockhash } = await connection.getLatestBlockhash();
transaction.recentBlockhash = blockhash;

// ❌ Bad - Reusing old blockhash
// Blockhashes expire after ~60 seconds

Set fee payer

Always specify the fee payer:

transaction.feePayer = new PublicKey(user.wallet.address);

Store signed transactions securely

If storing signed transactions, use secure storage:

// Encrypt before storing
const encrypted = encryptData(signedTransaction);
localStorage.setItem('signedTx', encrypted);

// Decrypt when broadcasting
const decrypted = decryptData(localStorage.getItem('signedTx'));
await connection.sendRawTransaction(decrypted);

Handle expiration

Signed transactions can expire if blockhash is old:

try {
  const signature = await connection.sendRawTransaction(signedTransaction);
} catch (error: any) {
  if (error.message?.includes('blockhash')) {
    alert('Transaction expired. Please sign again.');
    // Re-sign with fresh blockhash
  }
}

Validate before signing

Check transaction validity before signing:

// Validate recipient address
if (!isValidSolanaAddress(recipient)) {
  alert('Invalid recipient address');
  return;
}

// Check balance
const balance = await connection.getBalance(
  new PublicKey(user.wallet.address)
);

if (balance < transferAmount) {
  alert('Insufficient balance');
  return;
}

// Now sign
await signTransaction({ transaction });

Confirm after broadcasting

Always wait for confirmation after broadcasting:

const signature = await connection.sendRawTransaction(signedTransaction);

// Wait for confirmation with timeout
const confirmation = await connection.confirmTransaction(
  signature,
  'confirmed'
);

if (confirmation.value.err) {
  throw new Error('Transaction failed');
}

Troubleshooting

Blockhash expired error

Signed transactions expire if blockhash is too old:

// Ensure fresh blockhash when signing
const { blockhash, lastValidBlockHeight } = await connection.getLatestBlockhash();
transaction.recentBlockhash = blockhash;

// Check if still valid before broadcasting
const currentBlockHeight = await connection.getBlockHeight();

if (currentBlockHeight > lastValidBlockHeight) {
  alert('Transaction expired, please sign again');
  return;
}

await connection.sendRawTransaction(signedTransaction);

Signature verification failed

Ensure transaction is properly constructed:

// ✅ Correct - Set all required fields
transaction.recentBlockhash = blockhash;
transaction.feePayer = new PublicKey(user.wallet.address);

// All signers must be specified
transaction.sign(); // If additional signers needed

Cannot deserialize signed transaction

Use proper serialization/deserialization:

import { Transaction } from '@solana/web3.js';

// Serialize
const serialized = signedTransaction;

// Deserialize
const transaction = Transaction.from(serialized);

User cancelled signing

Handle cancellations gracefully:

const { signTransaction } = useSignTransaction({
  onError: (error: any) => {
    if (error.code === 'USER_REJECTED') {
      console.log('User cancelled signing');
      return;
    }
    console.error('Signing error:', error);
  }
});

Send Transaction

Sign and broadcast transactions

Sign Message

Sign messages with Solana wallet

Solana Web3.js

Official Solana JavaScript library

Transaction Format

Solana transaction structure

Next Steps

Learn about sending transactions
Understand Solana’s transaction lifecycle
Explore transaction confirmation strategies
Implement transaction retry logic for reliability

Embedded wallets

Using wallets

UI components

Funding

Sign Transaction

Sign Transaction

Overview

Signing vs Sending

React SDK

Parameters

Options Object

Hook Callbacks

Returns

Complete Examples

Sign and Broadcast Later

Batch Transaction Signing

Broadcasting Signed Transactions

With Custom Commitment

Transaction Serialization

Serialize to Base64

Deserialize from Base64

UI Customization

Best Practices

Troubleshooting

Send Transaction

Sign Message

Solana Web3.js

Transaction Format

Next Steps

Embedded wallets

Using wallets

UI components

Funding

​Sign Transaction

​Overview

​Signing vs Sending

​React SDK

​Parameters

​Options Object

​Hook Callbacks

​Returns

​Complete Examples

​Sign and Broadcast Later

​Batch Transaction Signing

​Broadcasting Signed Transactions

​With Custom Commitment

​Transaction Serialization

​Serialize to Base64

​Deserialize from Base64

​UI Customization

​Hide Modal

​Best Practices

​Troubleshooting

​Related Documentation

Send Transaction

Sign Message

Solana Web3.js

Transaction Format

​Next Steps

Sign Transaction

Overview

Signing vs Sending

React SDK

Parameters

Options Object

Hook Callbacks

Returns

Complete Examples

Sign and Broadcast Later

Batch Transaction Signing

Broadcasting Signed Transactions

With Custom Commitment

Transaction Serialization

Serialize to Base64

Deserialize from Base64

UI Customization

Hide Modal

Best Practices

Troubleshooting

Related Documentation

Next Steps