Welcome to NERO 402

NERO 402 is the first production implementation of an AA-native settlement scheme for the x402 V2 HTTP payment protocol. Where the upstream exact scheme requires the paying account to be an EOA capable of signing EIP-3009 typed data, the aa-native scheme defined here lets ERC-4337 smart contract wallets pay merchants directly. A paymaster sponsors the gas, so the agent never needs to hold the chain's native asset.

This site is the developer reference for everything in the stack:

• The four @nerochain/x402-* packages.
• The deployed SettlementContract on NERO mainnet and testnet.
• The reference facilitator service that speaks both exact and aa-native.
• The whitepaper that specifies the scheme.

Pick your path

If you are an agent author wanting to call paid APIs, start with Quickstart for agents.

If you are a merchant wanting to gate an endpoint behind payment, start with Quickstart for merchants.

If you want the protocol details, read the whitepaper or the aa-native scheme page.

What's distinctive about NERO 402

• Smart contract wallet payments. The paying account is an ERC-4337 SCW. EOAs are still supported via the exact scheme.
• Gas-sponsored from day one. Type-0 paymaster sponsorship means the agent's SCW spends zero NERO native on every paid call, including its own first-time deployment.
• Stable wire format. The envelope is the canonical x402 V2 payload (@x402/core@2.11.0); only the inner payload differs per scheme. Unmodified upstream exact clients interoperate with the reference facilitator out of the box.
• One on-chain settlement contract. Replay-protected, owner-allowlisted tokens, UUPS-upgradeable. Merchants are arguments to settle(), not separate deployments.

What's not done yet

The settlement contract has not been audited; v1.0 publication of the SDK packages waits on that. Mainnet deployments to date have processed sub-dollar quantities of USDT under controlled conditions. The whitepaper is published as a draft for community review prior to upstream submission.