How NERO 402 compares
NERO 402 is built for ERC-4337 agents. It is the only x402 settlement scheme that lets a smart-contract wallet pay an API and the only protocol without a native-asset requirement — the agent settles in stablecoins while a paymaster covers gas. Here is how that compares to the alternatives an autonomous agent actually has.
| Dimension | NERO 402 (aa-native) | x402 exact (upstream) | Stripe / card rails |
|---|---|---|---|
| Designed for | ERC-4337 smart-contract wallets (AI agents) | EOAs that can sign EIP-3009 | Human checkout / card-on-file |
| Native gas token required? | No — paymaster sponsors gas | Yes — payer holds native gas | N/A (fiat rails) |
| Settlement asset | Any allowlisted ERC-20 (USDT, USDC) | Only EIP-3009 tokens (e.g. USDC) | Fiat (cards, wallets) |
| Payment trigger | HTTP 402 + PAYMENT-SIGNATURE header | HTTP 402 + PAYMENT-SIGNATURE header | Hosted checkout / API keys |
| Agent onboarding | Self-serve key + sandbox; no forms | Self-serve key; needs native gas | Account approval, KYC, dashboard |
| Replay protection | On-chain settlement key + off-chain registry | EIP-3009 nonce on token | Idempotency keys (centralized) |
| Custody / trust | Non-custodial, on-chain, open source | Non-custodial, on-chain | Custodial intermediary |
Why agents choose NERO 402
An autonomous agent cannot fill out a "contact sales" form, pass KYC, or top up a native gas balance before every call. Card rails like Stripe assume a human and a custodial account. Upstream x402 exact assumes an EOA holding native gas and a token that implements EIP-3009 — assumptions that break on account-abstraction chains where every wallet is a contract.
NERO 402 removes both blockers: the wallet is an ERC-4337 smart-contract wallet, and gas is paymaster-sponsored, so the agent needs only the stablecoin it is spending. Onboarding is self-serve with a public testnet sandbox and a self-faucet token, and the entire stack is open source and non-custodial. For payer EOAs that do support EIP-3009, the same facilitator also speaks exact, so you are never locked out of upstream interoperability.
Start with the agent quickstart, or read the aa-native scheme for the full design rationale.