Swap API
Executable token swap calldata in one GET request. No API keys. No accounts. No SDK bloat.
Quick Start
Swap 1 ETH for USDC on Ethereum:
curl "https://api.swapapi.dev/v1/swap/1?\
tokenIn=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE&\
tokenOut=0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48&\
amount=1000000000000000000&\
sender=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
That's it. The response contains everything you need to sign and broadcast.
Example Response
{
"success": true,
"data": {
"status": "Successful",
"tokenFrom": {
"address": "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE",
"symbol": "ETH",
"name": "Ether",
"decimals": 18
},
"tokenTo": {
"address": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
"symbol": "USDC",
"name": "USD Coin",
"decimals": 6
},
"swapPrice": 2435.12,
"priceImpact": 0.0003,
"amountIn": "1000000000000000000",
"expectedAmountOut": "2435120000",
"minAmountOut": "2422947280",
"tx": {
"from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
"to": "0x011E52E4E40CF9498c79e329EBc29ed08c8B5abB",
"data": "0x2646478b...",
"value": "1000000000000000000",
"gasPrice": 30000000000,
"gas": "250000"
}
},
"timestamp": "2026-03-12T00:00:00.000Z"
}
| Field | Description |
|---|
success | Boolean indicating request success |
data.status | "Successful", "Partial", or "NoRoute" |
data.tokenFrom/tokenTo | Token metadata (address, symbol, decimals) |
data.swapPrice | Exchange rate |
data.priceImpact | Slippage impact (0.001 = 0.1%) |
data.expectedAmountOut | Estimated output in token's smallest unit |
data.minAmountOut | Guaranteed minimum (respects your maxSlippage) |
data.tx | Transaction object ready to sign and send |
API Reference
Endpoint: GET /v1/swap/{chainId}
Parameters:
| Param | Required | Description |
|---|
chainId | path | Chain ID (1=Ethereum, 8453=Base, 42161=Arbitrum, etc.) |
tokenIn | query | Input token address. Use 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE for native ETH |
tokenOut | query | Output token address |
amount | query | Input amount in smallest unit (e.g., wei for ETH) |
sender | query | Your wallet address (used to build the tx) |
maxSlippage | query | Optional. 0-1 (default: 0.005 = 0.5%) |
Response codes:
200 — Quote ready400 — Invalid params or unsupported chain429 — Rate limit exceeded (60/min per IP)502 — Upstream service error
More Curl Examples
Base (ETH → USDC)
curl "https://api.swapapi.dev/v1/swap/8453?\
tokenIn=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE&\
tokenOut=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&\
amount=500000000000000000&\
sender=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
Arbitrum (USDC → ETH with 1% slippage)
curl "https://api.swapapi.dev/v1/swap/42161?\
tokenIn=0xaf88d065e77c8cC2239327C5EDb3A432268e5831&\
tokenOut=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE&\
amount=1000000000&\
sender=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&\
maxSlippage=0.01"
Ethereum Mainnet (DAI → USDC)
curl "https://api.swapapi.dev/v1/swap/1?\
tokenIn=0x6B175474E89094C44Da98b954EedeAC495271d0F&\
tokenOut=0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48&\
amount=1000000000000000000000&\
sender=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
Polygon (MATIC → USDC)
curl "https://api.swapapi.dev/v1/swap/137?\
tokenIn=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE&\
tokenOut=0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174&\
amount=10000000000000000000&\
sender=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
Executing Swaps
The API gives you an unsigned transaction. Sign it and broadcast:
With Foundry cast
# 1. Set swap parameters
CHAIN_ID=8453
TOKEN_IN=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
TOKEN_OUT=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
AMOUNT=1000000000000000000
SENDER=0x... # Your address
PRIVATE_KEY=0x... # Your private key
RPC_URL=https://mainnet.base.org
# 2. Get swap quote
RESPONSE=$(curl -s "https://api.swapapi.dev/v1/swap/$CHAIN_ID?\
tokenIn=$TOKEN_IN&\
tokenOut=$TOKEN_OUT&\
amount=$AMOUNT&\
sender=$SENDER")
# 3. Parse the tx fields
TX_TO=$(echo "$RESPONSE" | jq -r '.data.tx.to')
TX_DATA=$(echo "$RESPONSE" | jq -r '.data.tx.data')
TX_VALUE=$(echo "$RESPONSE" | jq -r '.data.tx.value')
TX_GAS=$(echo "$RESPONSE" | jq -r '.data.tx.gas')
# 4. Sign and send
cast send \
--rpc-url "$RPC_URL" \
--private-key "$PRIVATE_KEY" \
"$TX_TO" \
--value "$TX_VALUE" \
--gas-limit "$TX_GAS" \
--data "$TX_DATA"
With viem
import { createWalletClient, http } from 'viem'
import { privateKeyToAccount } from 'viem/accounts'
import { base } from 'viem/chains'
const account = privateKeyToAccount('0x...')
const client = createWalletClient({
account,
chain: base,
transport: http()
})
const response = await fetch(
'https://api.swapapi.dev/v1/swap/8453?' +
'tokenIn=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE&' +
'tokenOut=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&' +
'amount=1000000000000000000&' +
'sender=' + account.address
)
const { data } = await response.json()
const hash = await client.sendTransaction({
to: data.tx.to,
data: data.tx.data,
value: BigInt(data.tx.value),
gas: BigInt(data.tx.gas)
})
await client.waitForTransactionReceipt({ hash })
MCP Server
For AI agents, Claude Desktop, Cursor, Cline, and other MCP clients:
Or add to Claude Desktop config:
{
"mcpServers": {
"swapapi": {
"command": "npx",
"args": ["@swapapi/mcp"]
}
}
}
See mcp/README.md for full MCP documentation.
OpenAPI Spec
See openapi.json for the full OpenAPI specification.
Limits
- Rate limit: 60 requests/minute per IP
- No authentication required
- Free to use
License
MIT