> ## Documentation Index
> Fetch the complete documentation index at: https://starkware-9575960b-eitan-accounts-update-0-14-1.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Tx Builder

> Batch multiple operations into a single atomic transaction using the fluent TxBuilder API

<img src="https://mintcdn.com/starkware-9575960b-eitan-accounts-update-0-14-1/l_oF5B_kl-ubyqT_/assets/starkzap/tx-builder.png?fit=max&auto=format&n=l_oF5B_kl-ubyqT_&q=85&s=9187ae6b155995289958f32ee4f8dba2" alt="Tx Builder hero" width="1024" height="576" data-path="assets/starkzap/tx-builder.png" />

## Overview

The `TxBuilder` provides a fluent API for batching multiple operations into a single atomic transaction. This saves gas and guarantees all-or-nothing execution—either all operations succeed together, or none of them execute.

## Basic Usage

```typescript theme={null}
const tx = await wallet
  .tx()
  .enterPool(poolAddress, Amount.parse("100", STRK))
  .send();
await tx.wait();
```

## Mixing Operations

Combine transfers, staking, approvals, and raw calls:

```typescript theme={null}
const tx = await wallet
  .tx()
  // Transfer tokens to multiple recipients
  .transfer(USDC, [
    { to: alice, amount: Amount.parse("50", USDC) },
    { to: bob, amount: Amount.parse("25", USDC) },
  ])
  // Stake in a pool (auto-detects enter vs. add)
  .stake(poolAddress, Amount.parse("100", STRK))
  // Claim rewards
  .claimPoolRewards(anotherPoolAddress)
  // Add raw contract calls
  .add({
    contractAddress: "0xDEX_CONTRACT",
    entrypoint: "swap",
    calldata: [/* ... */],
  })
  .send();

await tx.wait();
```

The `.stake()` method is smart — it automatically calls `enter_delegation_pool` for new members or `add_to_delegation_pool` for existing members.

## Preflight with Builder

```typescript theme={null}
const builder = wallet
  .tx()
  .stake(poolAddress, amount)
  .transfer(USDC, { to: alice, amount: usdcAmount });

const result = await builder.preflight();
if (!result.ok) {
  console.error("Transaction would fail:", result.reason);
} else {
  const tx = await builder.send();
  await tx.wait();
}
```

## Fee Estimation

```typescript theme={null}
const fee = await wallet
  .tx()
  .transfer(USDC, { to: alice, amount })
  .stake(poolAddress, stakeAmount)
  .estimateFee();

console.log("Estimated fee:", fee.overall_fee);
```

## Extracting Calls

You can also extract the raw calls for inspection:

```typescript theme={null}
const calls = await wallet
  .tx()
  .transfer(USDC, { to: alice, amount })
  .enterPool(poolAddress, stakeAmount)
  .calls();

console.log(`${calls.length} calls in this transaction`);
```

## Available Builder Methods

| Method                             | Description                                    |
| ---------------------------------- | ---------------------------------------------- |
| `.add(...calls)`                   | Add raw `Call` objects                         |
| `.approve(token, spender, amount)` | ERC20 approval                                 |
| `.transfer(token, transfers)`      | ERC20 transfer(s)                              |
| `.stake(pool, amount)`             | Smart stake (enter or add based on membership) |
| `.enterPool(pool, amount)`         | Enter pool as new member                       |
| `.addToPool(pool, amount)`         | Add to existing pool position                  |
| `.claimPoolRewards(pool)`          | Claim staking rewards                          |
| `.exitPoolIntent(pool, amount)`    | Start exit process                             |
| `.exitPool(pool)`                  | Complete exit after window                     |
| `.calls()`                         | Resolve all calls without sending              |
| `.estimateFee()`                   | Estimate gas cost                              |
| `.preflight()`                     | Simulate the transaction                       |
| `.send(options?)`                  | Execute all calls atomically                   |

## Best Practices

1. **Use the transaction builder** for complex operations to save gas
2. **Always preflight** non-trivial batches before submitting
3. **Combine related operations** into a single transaction when possible
4. **Use `.estimateFee()`** to show users the cost before executing

## Next Steps

* Learn about [Transaction Execution](/build/starkzap/transactions) for direct execution methods
* Explore [Staking and Delegation](/build/starkzap/staking) for staking operations
* Check the [Bitcoin, Stablecoins, and Token](/build/starkzap/erc20) module for token operations