> ## Documentation Index
> Fetch the complete documentation index at: https://docs.argyros.xyz/llms.txt
> Use this file to discover all available pages before exploring further.
# Build Transaction
> Build an unsigned swap transaction using POST /api/v1/swap.
# Build Transaction
`POST /api/v1/swap` builds a complete unsigned Solana transaction for a token swap. Sign it with the user's wallet and submit to the network.
## Request
User's wallet address (base58). This wallet signs and pays for the transaction.
Input token mint address.
Output token mint address.
Amount in smallest token units.
`ExactIn` or `ExactOut`.
Slippage tolerance in basis points. Default: 50 (0.5%).
Skip transaction simulation. Faster but no pre-flight validation. Only set `true` if you handle validation yourself.
## Example
```bash cURL theme={"theme":"github-dark"}
curl -X POST "https://api.argyros.xyz/api/v1/swap" \
-H "Content-Type: application/json" \
-d '{
"userWallet": "9WzDXwBbmkg8ZTbNMqUxvQRAyrZzDsGYdLVL9zYtAWWM",
"inputMint": "So11111111111111111111111111111111111111112",
"outputMint": "uSd2czE61Evaf76RNbq4KPpXnkiL3irdzgLFUMe3NoG",
"amount": "1000000000",
"swapMode": "ExactIn",
"slippageBps": 50
}'
```
```typescript TypeScript theme={"theme":"github-dark"}
const response = await fetch("https://api.argyros.xyz/api/v1/swap", {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({
userWallet: wallet.publicKey.toBase58(),
inputMint: "So11111111111111111111111111111111111111112",
outputMint: "uSd2czE61Evaf76RNbq4KPpXnkiL3irdzgLFUMe3NoG",
amount: "1000000000",
swapMode: "ExactIn",
slippageBps: 50,
}),
});
const { success, data, error } = await response.json();
if (!success) throw new Error(error);
console.log(`Transaction built. Expires at block ${data.lastValidBlockHeight}`);
```
```python Python theme={"theme":"github-dark"}
import requests
resp = requests.post("https://api.argyros.xyz/api/v1/swap", json={
"userWallet": "9WzDXwBbmkg8ZTbNMqUxvQRAyrZzDsGYdLVL9zYtAWWM",
"inputMint": "So11111111111111111111111111111111111111112",
"outputMint": "uSd2czE61Evaf76RNbq4KPpXnkiL3irdzgLFUMe3NoG",
"amount": "1000000000",
"swapMode": "ExactIn",
"slippageBps": 50,
})
result = resp.json()
if not result["success"]:
raise Exception(result["error"])
data = result["data"]
print(f"Transaction built. Expires at block {data['lastValidBlockHeight']}")
```
## Response
```json 200 — Success theme={"theme":"github-dark"}
{
"success": true,
"data": {
"transaction": "AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAQAHEAo...",
"lastValidBlockHeight": 245832190,
"amountIn": "1000000000",
"amountOut": "145320000",
"minAmountOut": "144593400",
"feeAmount": "0",
"simulation": {
"success": true,
"logs": [],
"computeUnitsConsumed": 85000,
"insufficientFunds": false,
"slippageExceeded": false
},
"computeUnitsEstimate": 85000,
"route": [
"So11111111111111111111111111111111111111112",
"uSd2czE61Evaf76RNbq4KPpXnkiL3irdzgLFUMe3NoG"
],
"hopCount": 1,
"pools": ["HJPjoWUrhoZzkNfRpHuieeFk9WcZWjwy6PBjZ81ngndJ"],
"isSplitRoute": false
}
}
```
## Response fields
Base64-encoded unsigned transaction. Deserialize, sign, and submit.
Transaction expires after this block height (\~60 seconds from creation).
Input amount in smallest units.
Estimated output amount in smallest units.
Minimum output after slippage (`ExactIn` only). Transaction reverts if actual output is less.
Maximum input after slippage (`ExactOut` only). Transaction reverts if actual input exceeds this.
Aggregator fee in output token units.
Simulation result (omitted if `skipSimulation: true`).
Whether the simulation passed.
Program log output.
CU used during simulation.
Error message if simulation failed.
Wallet doesn't have enough balance.
Price moved beyond tolerance.
Estimated compute units for execution.
Token path from input to output.
Number of swap hops.
Pool addresses used, in execution order.
Whether liquidity is split across multiple pools.
Percentage split per pool (only if `isSplitRoute` is true).
## Simulation
By default, the API simulates the transaction before returning it. This catches common issues early:
| `simulation` field | Meaning | What to do |
| -------------------------- | ------------------------------------------------- | -------------------------- |
| `insufficientFunds: true` | Wallet doesn't have enough tokens or SOL for fees | Show balance error to user |
| `slippageExceeded: true` | Price changed between quote and transaction build | Retry with a fresh quote |
| `success: false` + `error` | Other simulation failure | Check `logs` for details |
Set `skipSimulation: true` only if you need lower latency and handle validation yourself.
## What's next
After receiving the transaction, [sign and submit it](/docs/swap/send-transaction).