About NERO 402
NERO 402 is the first production implementation of an AA-native settlement scheme for the x402 V2HTTP payment protocol. It lets ERC-4337 smart-contract wallets pay merchants directly over HTTP 402, with a paymaster sponsoring gas so an autonomous agent settles in stablecoins while holding none of the chain's native token.
The project exists because x402's default exact scheme settles through EIP-3009 transferWithAuthorization, which only externally owned accounts can sign. On NERO Chain every wallet is a smart-contract wallet, so exact is effectively unusable. NERO 402 contributes a second scheme — aa-native — in which the wallet signs an ERC-4337 UserOperation that calls an on-chain settlement contract. The wire envelope stays identical to x402 V2, so unmodified upstream clients interoperate.
Who builds it
NERO 402 is an open-source project from NERO Chain, the team behind the NERO Chain account-abstraction Layer-1. The stack — an on-chain settlement contract, a reference facilitator service, five TypeScript SDK packages, a public playground, and this documentation — is developed in the open at github.com/nerochain/nero-x402 under the MIT license. Issues, pull requests, and design discussion are public; the path to upstream standardization runs through coinbase/x402#639.
Maturity and trust
The settlement contract is a UUPS-upgradeable, owner-allowlisted, replay-protected contract deployed on NERO mainnet (chainId 1689) and testnet (chainId 689). It has not yet been audited; the v1.0 release of the SDK is conditional on a clean external audit, and mainnet deployments to date have processed only sub-dollar test amounts. We publish our security policy and a coordinated-disclosure process, and we respond to reports at help-support@nerochain.io.