AI agents settle micro-payments mostly in USDC

The x402 protocol moved about $52.7 million across 198.9 million payments since May 2025, and 99.6% of that value was in USDC. When researchers removed self-payments and bulk flows, genuine commerce on x402 dropped to $25.6 million. A TRM Labs analysis estimates AI agent-specific commerce in the same window at roughly $150,000 to $1.9 million, depending on methodology.

Traffic on x402 is dominated by very small, repeated payments tied to machine-to-machine tasks and crypto trading. The average payment size on x402 is about $0.26, a level that traditional card networks generally cannot clear economically.

Researchers and protocol designers describe four main uses of money by agents: paying other machines, trading crypto, purchasing goods or services for humans, and receiving payments. Stablecoins, led by USDC, are the primary settlement medium for machine payments and crypto trading. Consumer-style purchases that require refunds and chargebacks continue to route over card networks.

Two technical approaches are in operation for machine micro-billing. Coinbase’s x402 model embeds payments into web requests, with a facilitator verifying signed authorizations and covering network fees. The Machine Payments Protocol, implemented by Stripe and Paradigm as Tempo, uses a session model: an agent authorizes a spending cap once and then streams micropayments while consuming a service. Early merchants using the session model include services that meter headless browser sessions, physical mail services, and retail merchants that accept automated orders.

On June 11, Coinbase introduced a product called Coinbase for Agents that links an AI agent to a Coinbase wallet under limits set by the account holder. The product focuses on portfolio management and trade execution; each trade’s cash leg typically begins or ends in USDC. Coinbase also offers rewards on idle USDC balances.

Nevermined provides a dual-rail solution for very small API calls. Its HTTP 402 handshake supports two settlement rails so the same integration can settle in crypto or with card credits. On the crypto rail, ERC-4337 smart accounts and buyer-signed EIP-712 terms let a merchant verify and broadcast a USDC transfer per API call without the broker holding keys. On the card rail, delegated Stripe, Braintree or Visa cards pay by pre-buying blocks of credits that the merchant burns per call. Nevermined charges merchants roughly 1%–2% of settled volume and can charge buyers on external services.

Card networks remain the primary rail for consumer-facing agent purchases that require dispute and chargeback protections. Payment products from major networks include scoped credentials, allow lists and transaction categories intended for agent-initiated payments.

On-chain totals require caution. Automated scripts, scheduled jobs and internal transfers can produce the same on-chain signatures as autonomous agents, making raw protocol volume an imperfect proxy for agent activity. TRM Labs identified agent-like behavior by looking for addresses that interact with multiple services; separate research flagged a large share of protocol transactions as artificial. Flows that pass through KYC-backed platforms or use delegated cards are harder to fake, providing stronger signals of genuine agent commerce.

Infrastructure for agent payments is in place across several rails. Current data show agent-driven spending remains a small fraction of overall protocol volume. Observers note that the share of filtered agent volume within protocols and merchant choices between per-call USDC settlement and prepaid card credits will determine which settlement rail gains scale.