USDC

USDC (USD Coin) is a stablecoin pegged 1:1 to the US dollar and issued by Circle. Each token is backed by reserves of cash and short-term US treasuries, with regular attestations published, so one USDC is designed to always be redeemable for one dollar.

Functionally, USDC is a dollar that moves on a blockchain: transfers settle in seconds, work across borders without banking hours, and can be initiated by software holding a signing key — no card network, account number, or human approval in the path. That last property is what makes it the workhorse currency of agentic commerce: an AI agent can hold and spend USDC directly.

Machine-to-machine payments need three things: price stability, low transfer cost, and programmability. USDC delivers all three. An agent paying $0.01 for an API call knows the amount will not drift in value between the request and on-chain confirmation — which a payment denominated in ETH or BTC cannot guarantee.

Sellers benefit from the same property in reverse: revenue earned across thousands of micro-payments arrives as a dollar-denominated asset, not a volatile token that must be hedged or hastily converted. Accounting stays in dollars end to end.

The x402 protocol uses USDC as its default settlement currency. A paid endpoint answers an unpaid request with HTTP 402 and a payment requirement naming an exact USDC amount and address. The agent's wallet signs the transfer, a facilitator verifies and submits it, and the payment confirms on Base — Coinbase's Ethereum Layer 2 — in roughly two seconds.

Settlement is final: there is no chargeback window, and the buyer receives a signed Ed25519 receipt plus a Base transaction hash as proof of payment. The seller's handler only runs after the USDC has settled.

USDC exists on many chains, but x402 settlement standardizes on Base because transfer fees there are a fraction of a cent and confirmation takes about two seconds. That fee profile is what makes one-cent payments viable — on Ethereum mainnet, gas alone could exceed a micro-payment many times over.

For comparison, card networks impose effective minimums around $0.30 per transaction in fixed fees. USDC on Base moves the economic floor low enough that the Loomal Index's minimum per-call price of $0.01 leaves real margin for the seller.

Every priced listing on the Loomal Index settles in USDC on Base. Sellers claim their MCP server or API listing, set a per-call price from $0.01 up, and receive USDC as agents pay; Loomal's fee is 5% on settled transactions, currently waived.

Received USDC can be held, used to pay for other agent tools, or converted to fiat through any major exchange or Circle directly. The console tracks settled revenue per listing, and each payment reconciles to a public transaction on Base.