API

This API provides methods to interact with Fastlane's MEV Protection auction system. All values in requests and responses must be hex strings (prefixed with '0x').

JSON RPC Methods

atlas_sendUnsignedTransaction

Submits a transaction to the Fastlane auction system for MEV protection.

Parameters

Type	Description
object	The transaction request details (see below)

Transaction Request

Name	Type	Description
transaction	object	The transaction details (see below)
refundRecipient	string	Address to receive a portion of the MEV (optional), hex encoded
refundPercent	string	Percentage of MEV to send to refundRecipient (0-90), hex encoded
bidTokenIsOutputToken	boolean	Whether to use the output token as the bid token
tokenIn	string	input token from user
tokenOut	string	final ouput token user receives
amountIn	string	input amount user swaps, hex encoded (e.g., "0x...")
amountOutMin	string	minimum amount user receives for the swap to be successful, hex encoded (e.g., "0x...")

Transaction Object

Name	Type	Description
chainId	string	Chain ID, hex encoded (e.g., "0x279f" for Monad Testnet)
from	string	User's address, hex encoded (e.g., "0x1234...")
to	string	dApp router address, hex encoded (e.g., "0x1234...")
value	string	Transaction value, hex encoded (e.g., "0x0")
data	string	Transaction data, hex encoded (e.g., "0x...")
maxFeePerGas	string	Maximum fee per gas, hex encoded (e.g., "0x...")

Returns

Type	Description
AtlasResponse	The transaction details to be signed and submitted, all values hex encoded

AtlasResponse

Name	Type	Description
from	string	User's address, hex encoded (e.g., "0x1234...")
to	string	Atlas router address, hex encoded (e.g., "0x1234...")
value	string	Transaction value, hex encoded (e.g., "0x0")
data	string	Transaction data, hex encoded (e.g., "0x...")
gas	string	Gas limit, hex encoded (e.g., "0x...")
maxFeePerGas	string	Maximum fee per gas, hex encoded (e.g., "0x...")

Example Request

{
  "jsonrpc": "2.0",
  "method": "atlas_sendUnsignedTransaction",
  "params": [{
    "transaction": {
      "chainId": "0x279f",
      "from": "0x1234567890123456789012345678901234567890",
      "to": "0x4a730A56344873FB28f7C3d65A67Fea56f5e0F46",
      "value": "0x0",
      "data": "0x...",
      "maxFeePerGas": "0x..."
    },
    "refundRecipient": "0x1234567890123456789012345678901234567890",
    "refundPercent": "0xa", // 10 in hex
    "bidTokenIsOutputToken": true,
    "tokenIn": "0xtokenIn", // use 0 address for native token
    "tokenOut": "0xtokenOut", // use 0 address for native token
    "amountIn": "0x..", // hex value
    "amountOutMin": "0x..", // hex value
  }],
  "id": 1
}

Example Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "from": "0x1234567890123456789012345678901234567890",
    "to": "0x4a730A56344873FB28f7C3d65A67Fea56f5e0F46",
    "value": "0x0",
    "data": "0x...",
    "gas": "0x...",
    "maxFeePerGas": "0x..."
  }
}

Environment Variables

• ATLAS_ROUTER=0xbB010Cb7e71D44d7323aE1C267B333A48D05907C
• ATLAS_AUCTIONEER=https://auctioneer-fra.fastlane-labs.xyz
• ATLAS_REFUND_RECIPIENT=<YOUR_PROTOCOL_REFUND_ADDRESS> (hex encoded)
• ATLAS_REFUND_PERCENT=<0-90> (decimal number)