Circle publishes USDC specification for Machine Payments Protocol

Circle just dropped a formal playbook for how machines should pay each other. The company published a USDC method specification for the Machine Payments Protocol (MPP), creating a standardized framework for AI agents and automated services to settle transactions in USDC across EVM-compatible blockchains and Solana.

What the Machine Payments Protocol actually does

MPP establishes an open standard for machine-to-machine payments. The protocol was developed in collaboration with Stripe and Tempo, two names that signal Circle is serious about bridging traditional payments infrastructure with crypto-native settlement.

The core idea is straightforward. AI agents need a way to transact autonomously, whether that means paying for compute resources, settling API calls, or handling microtransactions between services. MPP gives them a shared protocol to do exactly that, with USDC as the settlement asset.

MPP supports nanopayments as low as $0.000001 per transaction, enabled through EIP-3009 batching, a method that allows multiple transfer authorizations to be bundled efficiently.

The specification covers USDC transactions on EVM-compatible chains and Solana. Circle says USDC is supported natively on over 34 blockchains, which provides a broad foundation for MPP adoption across different ecosystems.

Circle’s broader Agent Stack

The MPP specification is part of Circle’s Agent Stack, which launched on May 12, 2026. The stack includes Agent Wallets, a Marketplace for discovering services, a Command Line Interface for developers, and the nanopayment infrastructure that makes sub-penny transactions viable.

Agent Wallets give automated services the ability to hold, send, and receive USDC without requiring a human custodian to manage each transaction. The Marketplace component provides a directory where agents can find and evaluate services they might want to pay for.

A crowded race for machine payment standards

Circle isn’t the only company eyeing machine-to-machine payments. The competing x402 standard has backing from Coinbase and support from major companies including Google and Visa.

USDC already operates across networks including Base, Solana, and Tempo. Adding a formal machine payment protocol on top of that infrastructure makes it stickier.

Stripe processes payments for millions of businesses globally and has been steadily expanding its crypto capabilities. Having Stripe involved in developing MPP suggests the protocol could eventually bridge the gap between traditional payment rails and crypto-native settlement in ways that matter for enterprise adoption.