How x402 Works

x402 is a payment protocol that lets a user authorize token transfers for paid requests. The facilitator verifies the authorization and settles it on-chain.

Flow

1. Authorization: The user signs an ERC-3009 TransferWithAuthorization message.
2. Verification: The backend calls /verify to validate recipient, amount, time window, balance, and signature.
3. Settlement: The backend calls /settle and the facilitator submits the on-chain transfer.
4. Access: The backend fulfills the request after settlement.

This implementation currently supports the exact payment scheme and handles v1 and v2 request formats.