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agent402.tools EIP-3009 Transfer Authorization Builder
x402
agent402.tools EIP-3009 Transfer Authorization Builder is a paid API for AI agents from agent402.tools, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).
Constructs the EIP-712 typed data payload for an EIP-3009 transferWithAuthorization gasless USDC transfer, ready for an agent to sign with its own key for x402 payments on EVM chains.
Price / call$0.003
Success—
StatusUnknown
How this service works
Build the EIP-3009 transferWithAuthorization typed data for a gasless USDC transfer on Base/Polygon/Arbitrum/Optimism/Ethereum/Monad/Celo/Avalanche/Sei - the exact EIP-712 object an agent signs with its OWN key to authorize an x402 payment. We construct it; we never sign or send. Non-custodial.
Output
Returns a fully constructed EIP-712 typed data object containing the domain separator (contract address, chain ID, USDC token details), the EIP-3009 message struct (from, to, value, validAfter, validBefore, nonce), and all fields required for the agent to call eth_signTypedData_v4 and produce a valid signature for a gasless USDC transfer. The service constructs but never signs.
Example use cases
Example prompt
“Build the EIP-3009 transferWithAuthorization typed data so I can sign a gasless USDC transfer of 0.05 USDC from my wallet 0xAbC...123 to 0xDeF...456 on Base, valid for 1800 seconds.”
Technical details
Endpoint
POSThttps://agent402.tools/api/transfer-authorizationWhen to prefer
Use this endpoint when an AI agent needs to autonomously authorize a gasless USDC payment using the x402 protocol on Base, Polygon, Arbitrum, Optimism, or Ethereum — specifically when you need the EIP-712 typed data structure for EIP-3009 transferWithAuthorization. Prefer this over manual construction to avoid encoding errors in domain separators or nonce derivation. Not needed if you are executing a standard on-chain USDC transfer with gas or using a different token.
Side effects
- Invalid Ethereum address format for 'from' or 'to' — returns 400 with address validation error
- Unsupported network value — returns 400 listing valid chain options
- Amount out of range or non-numeric — returns 400 with schema error
- Service unavailable or timeout fetching on-chain nonce — returns 502 or 503
- Missing required fields (from, to, amount) — returns 400 with field-level error detail
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| to | string | recipient address |
| from | string | payer address (the wallet that will sign) |
| amount | number | USDC amount (e.g. 0.01) |
| network | string | chain: base | polygon | arbitrum | optimism | ethereum | monad | celo | avalanche | sei | robinhood (default base) |
| validForSeconds | number | how long the authorization is valid (default 3600) |
Output
Schema · Response
{
"type": "json",
"example": {
"network": "base",
"typedData": {
"domain": {
"name": "USD Coin",
"chainId": 8453,
"version": "2",
"verifyingContract": "0x833589f…"
},
"message": {},
"primaryType": "TransferWithAuthorization"
}
}
}Tags
x402
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