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3Route Swap Quote & Transaction Builder
x402
3Route Swap Quote & Transaction Builder is a paid API for AI agents from api.3route.io, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-17).
Returns a best-priced swap quote and ready-to-sign transaction for exchanging one crypto token for another on a specified EVM chain.
Price / call$0.001
Success—
StatusUnknown
How this service works
Best-priced crypto token swaps for agents, traders and apps. Pay-per-call quote & swap API via x402/MPP. No API key or subscription.
Output
Returns a JSON object containing: a ready-to-sign transaction object (to, from, data, value, gas, gasPrice), the expected destination token amount (dstAmount), minimum guaranteed destination amount accounting for slippage (dstAmountMin), the source amount (srcAmount), and a gas estimate integer.
Example use cases
DeFi agent auto-rebalancing portfolio
“I want to rebalance my portfolio on chain 4663 — sell 500000000000000000 wei of the native asset from wallet 0xAbCd...1234 and buy USDC at 0x5fc5360d0400a0fd4f2af552add042d716f1d168, use 0.5% slippage and give me the transaction I need to sign.”
Best-price token swap for trading bot
“Get me the cheapest route to swap 2000000 USDC (address 0x5fc5360d0400a0fd4f2af552add042d716f1d168) for the native token on chain 42793 from wallet 0x2222222222222222222222222222222222222222 with 1% slippage — show me the expected output and the transaction data.”
Cross-token payment settlement
“Build a swap transaction on chain 128064 to sell exactly 1000000000000000000 wei of token 0xAaaa...0001 from address 0x3333333333333333333333333333333333333333 and receive token 0xBbbb...0002 at wallet 0x4444444444444444444444444444444444444444, with 2% slippage allowed.”
Technical details
Endpoint
GEThttps://api.3route.io/v1/%7BchainId%7D/swapWhen to prefer
Choose this endpoint when you need a pay-per-call, no-subscription DEX aggregator quote and executable swap transaction on one of the three supported EVM chains (4663, 42793, 128064). It is ideal for AI agents and bots that need on-demand pricing without managing API keys, and for apps requiring ready-to-sign transaction calldata rather than just a price estimate.
Side effects
- Unsupported chainId enum value returns an error — only 4663, 42793, and 128064 are valid
- Invalid token address format (not 0x + 40 hex chars) causes a schema validation error
- Insufficient liquidity for the requested token pair or amount returns no route found
- Amount of zero or non-integer amount string causes a bad request error
- Slippage out of bounds (>50 or <0) causes parameter validation failure
- Payment not fulfilled via x402/MPP results in 402 Payment Required before any quote is returned
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"tx": {
"to": "0x2222222222222222222222222222222222222222",
"gas": "210000",
"data": "0x1234",
"from": "0x1111111111111111111111111111111111111111",
"value": "1000000000000000000",
"gasPrice": "1000000000"
},
"gas": 210000,
"dstAmount": "950000",
"srcAmount": "1000000000000000000",
"dstAmountMin": "940500"
}
}Tags
x402
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