Citation-level USDC nanopayments for the agent economy
NanoProof is the open infrastructure layer that lets AI agents automatically pay creators in USDC whenever their work is cited — using the x402 protocol, settled on Arc, and verified on ArcScan.
No wallet. No subscription. No setup. Judge demo runs in 60 seconds.
How it works
Eight steps from citation to settlement
Every step is open, hash-chained, and verifiable onchain.
Creator publishes premium content
Publishes a research answer, source, citation, or any paywalled resource on NanoProof.
x402 payment request generated
NanoProof issues an HTTP 402 Payment Required challenge with a price in USDC and a validBefore window.
Supporter accesses the content
An AI agent or human client hits the URL and receives the x402 challenge in the PAYMENT-REQUIRED header.
Payment signed and submitted
The client signs an EIP-3009 transferWithAuthorization and posts it via PAYMENT-SIGNATURE.
Settled on Arc
A facilitator broadcasts the USDC transfer on Arc testnet (chain id 5042002). Sub-second BFT finality.
Settlement Proof generated
An immutable, hash-chained SettlementProof is created: hash = sha256(prevHash + canonical body).
Verified on ArcScan
Every settlement is verified against ArcScan Blockscout v2 API. Result stored as a VerificationEvent.
Dashboard updates live
Revenue, history, analytics, and protocol-wide metrics update in real time across the dashboard.
For Creators
Earn USDC the moment your work is cited. No ads. No subscription gates. Every citation triggers a payment.
For Agents
Pay for citations with a single HTTP header. No accounts, no SDKs, no tokens to manage. Just HTTP 402.
For the Web
Open infrastructure. MIT licensed. Apache 2.0 x402 standard. Anyone can run a node.
The protocol
x402 + EIP-3009 + Arc + ArcScan
Built on open standards. No proprietary payment rails.
x402
HTTP 402 Payment RequiredCoinbase's open standard for HTTP 402 payments. The server returns 402 with a PAYMENT-REQUIRED header containing a base64-encoded challenge. The client responds with PAYMENT-SIGNATURE. The server confirms with PAYMENT-RESPONSE.
EIP-3009
Gasless USDC transfersUSDC's native transferWithAuthorization lets the client sign an offchain authorization. The facilitator submits it onchain and pays gas. The client never needs ETH.
Arc
Stablecoin-native L1Circle's L1 built around USDC. Sub-second BFT finality, sub-cent fees, USDC-native gas. Chain id 5042002 on testnet.
ArcScan
Public onchain verificationBlockscout v2 explorer at testnet.arcscan.app. Every settlement is verified via its txHash. The result is stored as an append-only VerificationEvent.
{
"x402Version": 1,
"scheme": "exact",
"network": "eip155:5042002",
"resource": "/v1/research/cite",
"payTo": "0xCreator...",
"maxAmountRequired": "1000",
"asset": "0x3600...0000",
"nonce": "0xa1b2c3d4...",
"validBefore": "2026-07-03T15:00:00Z"
}Architecture
From citation to immutable proof
Why NanoProof
The first protocol to actually use HTTP 402
HTTP 402 has been reserved since 1991. NanoProof is the first production system that uses it the way the IETF intended — for autonomous machine-to-machine payments.
- Open standard — Apache 2.0, MIT licensed
- Sub-cent payments — $0.001 USDC per citation
- Sub-second finality — Arc BFT = 1 confirmation
- Gasless clients — EIP-3009 transfers
- Tamper-evident — hash-chained SettlementProofs
- Public verification — every tx on ArcScan
See the full demo in 60 seconds
No wallet. No crypto knowledge required. Click through the entire x402 → Arc → ArcScan flow.