Circle Nanopayments
TestnetCircle Nanopayments — Circle (USDC)
Overview
Circle Nanopayments is Circle's infrastructure for sub-cent USDC micropayments, optimized for AI agents that pay per-token, per-byte, or per-call. SettleGrid wires it as an EIP-3009 USDC rail on Base: the payer signs a one-time transfer authorization offline, SettleGrid verifies it without a chain round-trip, then settles it on-chain from its own gas wallet.
How It Works
Traditional on-chain transactions have a floor cost (gas fees) that makes sub-cent payments impractical. SettleGrid's Circle Nano rail uses an EIP-3009 transferWithAuthorization: the payer signs an EIP-712 authorization for a one-time USDC transfer to SettleGrid — amount, validity window, and nonce — and sends it in the x-circle-nano-auth header.
SettleGrid verifies that signature entirely offline: it recovers the EIP-712 signer, confirms the payee is SettleGrid and the authorized amount covers the tool price, all with no chain round-trip and no Circle account or API key.
When the consumer pays, SettleGrid submits the EIP-3009 transferWithAuthorization on-chain from its own gas wallet and waits for a confirmed receipt before recording the settlement — the payer signs once and SettleGrid pays the gas. Supported on Base mainnet and Base Sepolia.
How SettleGrid Integrates
SettleGrid supports Circle Nano as a USDC payment method. A consumer's agent sends an EIP-3009 transferWithAuthorization in the x-circle-nano-auth header; SettleGrid verifies it offline (EIP-712 signature recovery, payee, and amount), then submits it on-chain and waits for a confirmed receipt — all abstracted behind the same sg.wrap() interface. Verification itself needs no Circle account or API key.
Key Specs
| Protocol | Circle Nanopayments — Circle Nanopayments |
| Backer | Circle (USDC) |
| Detection Header | x-circle-nano-auth: <base64 EIP-3009 authorization> |
| Identity Type | eip3009 |
| Payment Type | nanopayment-channel (USDC) |
| Status | Testnet |
Code Example
Here is how a developer's tool works with Circle Nanopayments via SettleGrid:
import { settlegrid } from '@settlegrid/mcp'
const sg = settlegrid.init({
toolSlug: 'llm-proxy',
pricing: {
// Sub-cent pricing enabled by nanopayments
defaultCostCents: 0.1, // $0.001 per call
methods: {
'tokenize': { costCents: 0.01 },
'embed': { costCents: 0.5 },
'generate': { costCents: 2 },
},
},
// Circle Nanopayment channels are managed automatically
})
const embed = sg.wrap(async (args: { text: string }) => {
const embedding = await generateEmbedding(args.text)
return { content: [{ type: 'text', text: JSON.stringify(embedding) }] }
}, { method: 'embed' })Start monetizing with SettleGrid
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