Micropayments

A micropayment is a payment small enough that traditional payment infrastructure cannot process it profitably — typically anything from a few dollars down to fractions of a cent. The unit being paid for is correspondingly small: one API request, one web page scraped, one row of data returned.

The idea is decades old. What changed recently is the arrival of two things at once: blockchains with sub-cent transaction fees, and AI agents that consume services in exactly the tiny, irregular increments micropayments were designed for.

Card processing typically costs around $0.30 plus a percentage per transaction. Charge someone $0.02 for an API call and the processor fee is fifteen times the price. Traditional rails work around this by aggregating — subscriptions, prepaid credits, monthly invoices — which forces buyers to commit money before they know how much they will actually use.

Aggregation also requires an account relationship: signup, stored card, billing address, invoice history. That overhead is tolerable for a human buying one SaaS subscription. It collapses when the buyer is an AI agent that needs to touch fifty different services once each during a single task.

Stablecoin settlement on low-fee Layer 2 chains removes the fixed-cost floor. On Base, an Ethereum L2, a USDC transfer settles in roughly two seconds for a fee that is a small fraction of a cent. At that cost structure, charging $0.01 for a single call is a perfectly sound business: the payment is final on-chain, there is no chargeback window, and no invoice needs to exist.

The x402 protocol packages this into an HTTP flow. A server answers an unpaid request with HTTP 402 Payment Required and a price; the caller's wallet signs a USDC payment and retries; the server verifies, settles on Base, and serves the response. Each request is its own complete commercial transaction.

Agents are the first customers for whom micropayments beat every alternative. An agent researching a topic might need three searches from one provider, one PDF extraction from another, and a geocoding lookup from a third. Subscribing to all three providers would cost orders of magnitude more than the work performed; per-call micropayments cost exactly what was consumed.

Micropayments also make spend controllable. An agent's wallet can enforce a per-call ceiling and a total budget, turning cost control into a wallet policy rather than a contract negotiation.

Loomal's marketplace applies micropayments to MCP servers and APIs: a developer claims their listing, sets a per-call USDC price (minimum $0.01), and any x402-capable agent can pay and call it. Sellers receive a signed Ed25519 receipt and a Base transaction hash for every settled call, so revenue is auditable down to the individual request. Loomal charges a 5% fee on settled transactions, currently waived.