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Fly Trade EVM Swap API — Agent Reference

Overview

Base URL: https://api.fly.trade

Execute a token swap on EVM networks in 3 steps:

GET /aggregator/quote → receive quoteId + pricing
GET /aggregator/transaction → receive transaction payload
Sign and submit transaction to the network

Shortcut: Use GET /aggregator/quote/transaction to get both quote and transaction in one call (no gas estimation).

Decision Tree for Agent Use

Want to swap tokens?
│
├─ Standard swap (user pays gas in native token)
│   ├─ Need gas estimate?  → Step 1 (quote) + Step 2 (transaction, estimateGas=true) + Step 3
│   └─ No gas estimate needed? → Combined /quote/transaction + Step 3
│
└─ Calling from a smart contract?
    └─ GET /quote/transaction (estimateGas=false, fromAddress=CONTRACT) → forward data as calldata

Supported Networks

Use the network string (not chain ID) in all requests.

network value

Chain

ethereum

Ethereum Mainnet

polygon

Polygon

bsc

BNB Smart Chain

arbitrum

Arbitrum One

optimism

Optimism

base

Base

avalanche

Avalanche C-Chain

blast

Blast

manta

Manta Pacific

scroll

Scroll

fantom

Fantom

polygonzk

Polygon zkEVM

zksync

zkSync Era

linea

Linea

sonic

Sonic

megaeth

MegaETH

fogo

Fogo

stable

Stable

plasma

Plasma

monad

Monad

hyperevm

HyperEVM

eclipse

Eclipse

unichain

Unichain

berachain

Berachain

abstract

Abstract

ink

Ink

taiko

Taiko

metis

Metis

solana

Solana

morph

Morph

zerogravity

katana

Katana

tempo

Tempo

telos

Telos

pharos

Pharos

Full list: GET /token-manager/networks or check Swagger at https://api.fly.trade/swagger.

These 5 endpoints cover most agent use cases:

Step 1 — Get Quote

GET /aggregator/quote

Fetches a quote estimating the output amount you'll receive for swapping a given input asset. Use this to preview the exchange rate, fees, and expected output before committing to a transaction.

Required Parameters

Parameter

Type

Description

network

string

Network name (e.g. ethereum)

fromTokenAddress

string

The token address of the token to sell. Use 0x0000000000000000000000000000000000000000 for native token (ETH/MATIC/BNB)

toTokenAddress

string

Token to buy. Use 0x0000000000000000000000000000000000000000 for native token (ETH/MATIC/BNB)

sellAmount

string

The amount of the token to sell.

slippage

number

Max slippage. 0.005 = 0.5%, 0.01 = 1%

fromAddress

string

Wallet address sending the swap

toAddress

string

Wallet address receiving tokens

gasless

boolean

Always set gasless: false. This ensures the user pays gas in the native token. Gasless transactions are deprecated and will be removed in a future release.

Optional Parameters

Parameter

Type

Description

affiliateAddress

string

Address to receive affiliate fee

affiliateFee

number

Fee percentage. 0.01 = 1%. Deducted from fromToken

Example Request

GET https://api.fly.trade/aggregator/quote?network=ethereum&fromTokenAddress=0x0000000000000000000000000000000000000000&toTokenAddress=0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48&fromAddress=0xff270dc360ef80314c7d6b2564fe76eaf3979b1a&toAddress=0xff270dc360ef80314c7d6b2564fe76eaf3979b1a&sellAmount=1000000000000000000&slippage=0.005&gasless=false```

Response Schema (Standard Swap)

{
  "id": "8de05661-09d6-4b82-ab63-1e32ee1fa297",   // ← save as quoteId
  "amountOut": "1956398549",                        // expected output in smallest unit
  "targetAddress": "0xa6e941eab67569ca4522f70d343714ff51d571c4",  // router address (use for ERC-20 approval)
  "fees": [
    { "type": "gas", "value": "0.0150" }
  ],
  "resourceEstimate": {
    "gasLimit": "191157"
  }
}

Critical Constraints

Quote expires in 5 minutes. After expiry, the quoteId is invalid. Fetch a new quote.
Single-use. Each quoteId can only be used once with /aggregator/transaction. If consumed or expired, fetch a new quote.
ERC-20 approval required before executing. The spender is targetAddress from the quote response.

Step 2 — Get Transaction Payload

GET /aggregator/transaction

Required Parameters

Parameter

Type

Description

quoteId

string

The id value returned from Step 1

Optional Parameters

Parameter

Type

Default

Description

estimateGas

boolean

true

When true, validates token approval and balance before returning. Fails with "Couldn't estimate gas" if checks fail. Set to false for contract integrations.

Example Request

GET https://api.fly.trade/aggregator/transaction?quoteId=8de05661-09d6-4b82-ab63-1e32ee1fa297

Response Schema

{
  "from": "0xff270dc360ef80314c7d6b2564fe76eaf3979b1a",
  "to": "0xa6e941eab67569ca4522f70d343714ff51d571c4",   // router contract
  "data": "0x73fc4457...",                               // encoded calldata
  "chainId": 1,
  "type": 2,                                             // EIP-1559 (type 2) or legacy (type 0)
  "gasLimit": "314086",
  "maxFeePerGas": "228922087",                           // present for EIP-1559 chains
  "maxPriorityFeePerGas": "190605439",                   // present for EIP-1559 chains
  "value": "10000000000000000"                           // ETH value in wei (0 for ERC-20 swaps)
}

Note: Some chains return legacy format with gasPrice instead of maxFeePerGas/maxPriorityFeePerGas. Ensure your signer/library handles both.

Alternative: Combined Quote + Transaction (Single Request)

GET /aggregator/quote/transaction

Accepts all parameters from /aggregator/quote. fromAddress and toAddress are required. Gas is not estimated.

Example Request

GET https://api.fly.trade/aggregator/quote/transaction?network=base&fromTokenAddress=1&toTokenAddress=2&sellAmount=3&slippage=1&gasless=false&toAddress=111&fromAddress=111```

Response Schema

{
  "quote": {
    "id": "...",
    "amountOut": "...",
    "targetAddress": "...",
    "fees": [...],
    "resourceEstimate": { "gasLimit": "..." }
  },
  "transaction": {
    "from": "...",
    "to": "...",
    "data": "...",
    "chainId": 1,
    "type": 2,
    "gasLimit": "...",
    "maxFeePerGas": "...",
    "maxPriorityFeePerGas": "...",
    "value": "..."
  }
}

Step 3 — Execute the Transaction

Submit the transaction object from Step 2 directly to the network using any EVM-compatible library.

TypeScript (ethers.js):

const tx = await signer.sendTransaction({
  to: transaction.to,
  data: transaction.data,
  value: transaction.value,
  gasLimit: transaction.gasLimit,
  // For EIP-1559:
  maxFeePerGas: transaction.maxFeePerGas,
  maxPriorityFeePerGas: transaction.maxPriorityFeePerGas,
  // For legacy chains, use gasPrice instead
});
const receipt = await tx.wait();

ERC-20 Token Approval

Before swapping an ERC-20 token, the fromAddress must approve the router contract (targetAddress from the quote) to spend the token.

const token = new ethers.Contract(fromTokenAddress, [
  'function allowance(address owner, address spender) view returns (uint256)',
  'function approve(address spender, uint256 amount) returns (bool)'
], signer);

const allowance = await token.allowance(userAddress, routerAddress);
if (allowance.lt(sellAmount)) {
  const approveTx = await token.approve(routerAddress, ethers.constants.MaxUint256);
  await approveTx.wait();
}

Smart Contract Integration

When calling from a contract, always set estimateGas=false or use the combined /aggregator/quote/transaction endpoint with fromAddress set to your contract address.

// Get transaction data targeting your contract as sender
const url = new URL('https://api.fly.trade/aggregator/quote/transaction');
url.searchParams.set('fromAddress', CONTRACT_ADDRESS);
url.searchParams.set('estimateGas', 'false');
// ... other params

const { transaction } = await fetch(url.toString()).then(r => r.json());

// Pass transaction.data as calldata to your contract
await mySwapContract.executeSwap(fromToken, amountIn, transaction.data, { value: 0 });

Contract requirements:

Approve the Fly router for ERC-20 tokens before calling
Forward transaction.data as calldata to the router (targetAddress)
Forward the correct msg.value for native token swaps

PreviousRequesting and Using API Key

Last updated 24 days ago

hashtagFly Trade EVM Swap API — Agent Reference

hashtagOverview

hashtagDecision Tree for Agent Use

hashtagSupported Networks

hashtagThese 5 endpoints cover most agent use cases:

hashtagStep 1 — Get Quote

hashtagRequired Parameters

hashtagOptional Parameters

hashtagExample Request

hashtagResponse Schema (Standard Swap)

hashtagCritical Constraints

hashtagStep 2 — Get Transaction Payload

hashtagRequired Parameters

hashtagOptional Parameters

hashtagExample Request

hashtagResponse Schema

hashtagAlternative: Combined Quote + Transaction (Single Request)

hashtagExample Request

hashtagResponse Schema

hashtagStep 3 — Execute the Transaction

hashtagERC-20 Token Approval

hashtagSmart Contract Integration

Fly Trade EVM Swap API — Agent Reference

Overview

Decision Tree for Agent Use

Supported Networks

These 5 endpoints cover most agent use cases:

Step 1 — Get Quote

Required Parameters

Optional Parameters

Example Request

Response Schema (Standard Swap)

Critical Constraints

Step 2 — Get Transaction Payload

Required Parameters

Optional Parameters

Example Request

Response Schema

Alternative: Combined Quote + Transaction (Single Request)

Example Request

Response Schema

Step 3 — Execute the Transaction

ERC-20 Token Approval

Smart Contract Integration