# Signing and Execution

> Sign transactions and execute them on the Sui network

Once you've built a transaction, you need to sign it and submit it to the network. For background on
how transaction signing and finality work at the protocol level, see the Sui documentation on
[transaction lifecycle](https://docs.sui.io/concepts/transactions/transaction-lifecycle) and
[transaction auth](https://docs.sui.io/concepts/transactions/transaction-auth).

## Simulating transactions

Use `simulateTransaction` to dry-run a transaction without executing it. This is useful for
estimating gas costs, checking return values, and validating transactions before executing.

```typescript

const grpcClient = new SuiGrpcClient({
	network: 'mainnet',
	baseUrl: 'https://fullnode.mainnet.sui.io:443',
});

const result = await grpcClient.simulateTransaction({
	transaction: tx,
	include: {
		effects: true,
		balanceChanges: true,
		commandResults: true,
	},
});

if (result.$kind === 'FailedTransaction') {
	console.error('Simulation failed:', result.FailedTransaction.status.error?.message);
} else {
	console.log('Balance changes:', result.Transaction.balanceChanges);
	console.log('Command results:', result.commandResults);
}
```

### `include` options

The `include` parameter controls what data is returned from the simulation. All fields are optional
and default to `false`:

| Field            | Description                                                                            |
| ---------------- | -------------------------------------------------------------------------------------- |
| `effects`        | Execution effects: created, mutated, and deleted objects, gas usage                    |
| `events`         | Move events emitted during execution                                                   |
| `balanceChanges` | Token balance changes for each affected address and coin type                          |
| `objectTypes`    | Map of object ID to type string for all changed objects                                |
| `transaction`    | The full transaction data (sender, commands, gas config)                               |
| `bcs`            | Raw BCS-encoded transaction bytes                                                      |
| `commandResults` | BCS-encoded return values and mutated references from each command _(simulation only)_ |

The `commandResults` field is unique to simulation. It is not available on `executeTransaction`.
Each entry contains `returnValues` and `mutatedReferences`, both as BCS-encoded `Uint8Array` values
that you can decode with the [BCS library](/bcs).

## With a keypair (backend or scripts)

The simplest approach. The keypair signs the transaction and submits it to the network in one call:

```typescript

const keypair = Ed25519Keypair.fromSecretKey('suiprivkey1...');
const grpcClient = new SuiGrpcClient({
	network: 'mainnet',
	baseUrl: 'https://fullnode.mainnet.sui.io:443',
});

const result = await keypair.signAndExecuteTransaction({
	transaction: tx,
	client: grpcClient,
});
```

`fromSecretKey` accepts a Bech32-encoded private key (`suiprivkey1...`) or a raw 32-byte
`Uint8Array`. You can also use `Ed25519Keypair.deriveKeypair(mnemonic)` to derive from a mnemonic
phrase.

This method automatically sets the sender to the keypair's address, builds the transaction, signs
it, and executes it. The result includes the transaction data and effects by default.

Available keypair types:

- `Ed25519Keypair` from `@mysten/sui/keypairs/ed25519`
- `Secp256k1Keypair` from `@mysten/sui/keypairs/secp256k1`
- `Secp256r1Keypair` from `@mysten/sui/keypairs/secp256r1`
- `PasskeyKeypair` from `@mysten/sui/keypairs/passkey`

## With dapp-kit (React frontend)

In a React app, use the `useSignAndExecuteTransaction` hook. The user's connected wallet signs and
submits the transaction:

```tsx

function SendButton() {
	const { mutate: signAndExecute } = useSignAndExecuteTransaction();

	function handleClick() {
		const tx = new Transaction();
		// ... build your transaction ...

		signAndExecute(
			{ transaction: tx },
			{
				onSuccess: (result) => {
					console.log('Transaction digest:', result.digest);
				},
				onError: (error) => {
					console.error('Transaction failed:', error);
				},
			},
		);
	}

	return <button onClick={handleClick}>Send</button>;
}
```

See the [dapp-kit documentation](/dapp-kit) for full setup instructions.

## Sign without executing

Sometimes you need the signature without immediately executing, such as for multi-sig, sponsored
transactions, or delayed execution.

### With a keypair

```typescript
// Build the transaction bytes first
tx.setSender(keypair.toSuiAddress());
const bytes = await tx.build({ client: grpcClient });

// Sign the bytes
const { signature } = await keypair.signTransaction(bytes);
```

### With dapp-kit

```tsx

function SignButton() {
	const { mutate: signTransaction } = useSignTransaction();

	function handleClick() {
		const tx = new Transaction();
		// ... build your transaction ...

		signTransaction(
			{ transaction: tx },
			{
				onSuccess: ({ bytes, signature }) => {
					// Send bytes + signature to your backend, sponsor, etc.
				},
			},
		);
	}

	return <button onClick={handleClick}>Sign</button>;
}
```

## Manual execution

When you already have the transaction bytes and signature(s), execute directly through the client:

```typescript
const result = await grpcClient.executeTransaction({
	transaction: bytes, // Uint8Array
	signatures: [signature], // string[]
	include: {
		effects: true,
		events: true,
		balanceChanges: true,
		objectTypes: true,
	},
});
```

The `include` parameter controls what data is returned with the result:

| Field            | Description                                              |
| ---------------- | -------------------------------------------------------- |
| `transaction`    | The full transaction data (sender, commands, gas)        |
| `effects`        | Execution effects (created, mutated, or deleted objects) |
| `events`         | Move events emitted during execution                     |
| `balanceChanges` | Token balance changes for each affected address          |
| `objectTypes`    | Map of object ID to type for changed objects             |
| `bcs`            | Raw BCS bytes of the transaction                         |

## Observing results

### Checking success or failure

Every transaction result is a discriminated union. Always check which variant you received:

```typescript
const result = await keypair.signAndExecuteTransaction({
	transaction: tx,
	client: grpcClient,
});

if (result.$kind === 'FailedTransaction') {
	const { status } = result.FailedTransaction;
	console.error('Transaction failed:', status.error?.message);
} else {
	console.log('Transaction succeeded:', result.Transaction.digest);
}
```

You can also use the shorthand:

```typescript
const tx = result.Transaction ?? result.FailedTransaction;
if (!tx.status.success) {
	throw new Error(`Failed: ${tx.status.error?.message}`);
}
```

### Waiting for indexing

After a transaction executes, read APIs (like `getBalance` or `getObject`) might not immediately
show the effects. You must also wait before executing a subsequent transaction that depends on
objects created or modified by the first one. Use `waitForTransaction` to ensure consistency:

```typescript
const result = await keypair.signAndExecuteTransaction({
	transaction: tx,
	client: grpcClient,
});

// Wait for the transaction to be indexed
await grpcClient.waitForTransaction({ result });

// Now reads will reflect the transaction's effects
const { balance } = await grpcClient.getBalance({ owner: myAddress });
```

You can also wait by digest:

```typescript
await grpcClient.waitForTransaction({ digest: result.Transaction.digest });
```

## Gas configuration

Every Sui transaction costs gas. The SDK handles gas automatically in most cases. It sets the gas
price, estimates the budget, and selects how to pay. You only need to configure gas explicitly for
special cases.

### Defaults

When you don't configure gas explicitly, the SDK:

1. **Gas price**: Uses the network's reference gas price
2. **Gas budget**: Simulates the transaction and uses the result to set an appropriate budget
3. **Gas payment**: Uses address balances, falling back to coin objects when the balance is below
   the budget

For most transactions, the defaults work well and you don't need to change anything.

### Explicit gas settings

```typescript
// Override the reference gas price
tx.setGasPrice(1500);

// Override the simulated budget (in MIST)
tx.setGasBudget(50_000_000);
```

### Gas payment with coin objects

Specify exactly which coins to use for gas. The system merges these coins into a single gas coin
before execution:

```typescript
tx.setGasPayment([
	{ objectId: '0xCoin1', version: '1', digest: 'abc...' },
	{ objectId: '0xCoin2', version: '2', digest: 'def...' },
]);
```

The coins you provide must not overlap with any object inputs in your transaction.

### Gas payment with address balance

To pay gas from your address balance instead of coin objects, pass an empty array:

```typescript
tx.setGasPayment([]);
```

This is particularly useful for [offline building](./offline) and
[sponsored transactions](#sponsored-transactions), because there are no coin object versions to look
up or coordinate.

### The gas coin (`tx.gas`)

`tx.gas` references the coin used for gas payment. You can split SUI from it, merge coins into it,
or transfer it to another address:

```typescript
const [coin] = tx.splitCoins(tx.gas, [1_000_000_000]);
tx.transferObjects([coin], '0xRecipientAddress');
```

> **Warning:** `tx.gas` only works when gas is paid from coin objects. If gas is paid from address balances
> (through `setGasPayment([])`), `tx.gas` is not available. Use [`tx.coin()`](./coins-and-balances)
> instead, which works in both cases.

## Sponsored transactions

In a sponsored transaction, someone other than the sender pays for gas. There are two flows
depending on whether gas is paid from coin objects or address balances.

### Coin-based sponsorship

The traditional flow where the sponsor provides specific gas coin objects:

```typescript
// 1. User builds transaction kind bytes (no gas info)
const tx = new Transaction();
// ... add commands ...
const kindBytes = await tx.build({ client: grpcClient, onlyTransactionKind: true });

// 2. Sponsor wraps with gas info
const sponsoredTx = Transaction.fromKind(kindBytes);
sponsoredTx.setSender(userAddress);
sponsoredTx.setGasOwner(sponsorAddress);
sponsoredTx.setGasPayment(sponsorGasCoins);

// 3. Build the full transaction
const fullBytes = await sponsoredTx.build({ client: grpcClient });

// 4. Both parties sign
const { signature: userSignature } = await userKeypair.signTransaction(fullBytes);
const { signature: sponsorSignature } = await sponsorKeypair.signTransaction(fullBytes);

// 5. Execute with both signatures
const result = await grpcClient.executeTransaction({
	transaction: fullBytes,
	signatures: [userSignature, sponsorSignature],
});
```

> **Warning:** The user must wait for the sponsor to set gas coins before signing, because gas coins are part of
> the signed transaction data.

### Address balance sponsorship

When the sponsor pays from their address balance instead of specific coins, the flow is simpler
because there are no coin object references to coordinate:

```typescript
// 1. User builds and signs the transaction first
const tx = new Transaction();
tx.setSender(userAddress);
tx.setGasOwner(sponsorAddress);
tx.setGasPayment([]); // empty array = use address balance for gas
// ... add commands ...

const bytes = await tx.build({ client: grpcClient });
const { signature: userSignature } = await userKeypair.signTransaction(bytes);

// 2. Sponsor signs (can happen asynchronously)
const { signature: sponsorSignature } = await sponsorKeypair.signTransaction(bytes);

// 3. Either party executes
const result = await grpcClient.executeTransaction({
	transaction: bytes,
	signatures: [userSignature, sponsorSignature],
});
```

The key advantage: the sender can sign before the sponsor, enabling simpler async flows. No need to
coordinate gas coin selection.

### Sending tokens in sponsored transactions

When building sponsored transactions, set `useGasCoin: false` so the SDK doesn't try to split the
gas coin (which belongs to the sponsor):

```typescript

const tx = new Transaction();

// Send to address balance (preferred)
tx.moveCall({
	target: '0x2::balance::send_funds',
	typeArguments: ['0x2::sui::SUI'],
	arguments: [
		tx.balance({ balance: 1_000_000_000n, useGasCoin: false }),
		tx.pure.address('0xRecipientAddress'),
	],
});

// Or send as a coin object
tx.transferObjects([tx.coin({ balance: 1_000_000_000, useGasCoin: false })], '0xRecipientAddress');
```