> ## Documentation Index
> Fetch the complete documentation index at: https://docs.krokoswap.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Swap

> Generate Universal Router calldata for swap execution

# Swap API

Generates ready-to-use transaction calldata for executing a swap via the Universal Router. The response can be sent directly as a transaction.

## POST /api/v1/swap

### Request Body

```json theme={null}
{
  "tokenIn": "0xB190a6A7fC2873f1Abf145279eD664348d5Ef630",
  "tokenOut": "0x3Ac3B30b7f18AEFD4590D7FE4d9C5944aaeB7220",
  "amountIn": "1000000000000000000",
  "tradeType": 0,
  "slippage": 0.5,
  "recipient": "0xYourAddress",
  "deadline": 1200
}
```

| Field       | Type     | Required    | Description                                         |
| ----------- | -------- | ----------- | --------------------------------------------------- |
| `tokenIn`   | `string` | Yes         | Input token address                                 |
| `tokenOut`  | `string` | Yes         | Output token address                                |
| `amountIn`  | `string` | Conditional | Input amount (required when `tradeType=0`)          |
| `amountOut` | `string` | Conditional | Output amount (required when `tradeType=1`)         |
| `tradeType` | `number` | No          | `0` = Exact Input (default), `1` = Exact Output     |
| `slippage`  | `number` | No          | Slippage tolerance as percentage (default: `0.5`)   |
| `recipient` | `string` | Yes         | Address to receive output tokens                    |
| `deadline`  | `number` | No          | Seconds until expiration (default: `1200` = 20 min) |

### Response

```json theme={null}
{
  "to": "0x440d7f5FE865eFCcfdCB1ee9a000C114163689ba",
  "data": "0x3593564c...",
  "value": "0",
  "gasEstimate": "100000",
  "tradeType": 0,
  "quote": {
    "tokenIn": "0xb190...",
    "tokenOut": "0x3ac3...",
    "amountIn": "1000000000000000000",
    "amountOut": "1007249042881810956",
    "minAmountOut": "1002212797667401901",
    "priceImpact": 0.3,
    "protocol": "v2",
    "path": ["0xb190...", "0x3ac3..."],
    "fees": [0],
    "hops": 1
  },
  "deadline": "1764573986",
  "slippage": 0.5,
  "permit2": "0xc320bc492Bb56169aBE18D3C0a2048c45febC897"
}
```

| Field                | Description                                                                 |
| -------------------- | --------------------------------------------------------------------------- |
| `to`                 | Universal Router address — use as transaction `to`                          |
| `data`               | Encoded calldata — use as transaction `data`                                |
| `value`              | Native KAS amount — use as transaction `value` (non-zero when input is KAS) |
| `gasEstimate`        | Estimated gas units                                                         |
| `quote.minAmountOut` | Minimum output (Exact Input) — on-chain slippage protection                 |
| `quote.maxAmountIn`  | Maximum input (Exact Output) — on-chain slippage protection                 |
| `permit2`            | Permit2 contract address                                                    |

### Slippage Protection

| Trade Type       | Field          | Formula                            |
| ---------------- | -------------- | ---------------------------------- |
| Exact Input (0)  | `minAmountOut` | `amountOut × (1 - slippage / 100)` |
| Exact Output (1) | `maxAmountIn`  | `amountIn × (1 + slippage / 100)`  |

These limits are enforced **on-chain** by the Universal Router. The transaction reverts if the actual execution exceeds the slippage bounds.

### Usage

```typescript theme={null}
// 1. Get calldata
const res = await fetch('/swap-api/api/v1/swap', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    tokenIn, tokenOut, amountIn,
    tradeType: 0,
    slippage: 0.5,
    recipient: userAddress,
    deadline: 1200
  })
});
const swapData = await res.json();

// 2. Send transaction
const tx = await signer.sendTransaction({
  to: swapData.to,
  data: swapData.data,
  value: swapData.value
});
```

### Examples

<CodeGroup>
  ```json Exact Input Request theme={null}
  {
    "tokenIn": "0xB190a6A7fC2873f1Abf145279eD664348d5Ef630",
    "tokenOut": "0x3Ac3B30b7f18AEFD4590D7FE4d9C5944aaeB7220",
    "amountIn": "1000000000000000000",
    "tradeType": 0,
    "slippage": 0.5,
    "recipient": "0xUserAddress",
    "deadline": 1200
  }
  ```

  ```json Exact Output Request theme={null}
  {
    "tokenIn": "0xB190a6A7fC2873f1Abf145279eD664348d5Ef630",
    "tokenOut": "0x3Ac3B30b7f18AEFD4590D7FE4d9C5944aaeB7220",
    "amountOut": "1000000000000000000",
    "tradeType": 1,
    "slippage": 0.5,
    "recipient": "0xUserAddress",
    "deadline": 1200
  }
  ```
</CodeGroup>