what's Machine Payments Protocol?

Machine Payments Protocol (MPP) is an open, extensible standard for programmatic machine-to-machine payments over HTTP, enabling AI agents and services to handle microtransactions, recurring payments, and sessions without human intervention. Co-authored by Tempo (a blockchain for scalable payments) and Stripe, it uses HTTP status code 402 "Payment Required" to negotiate payments dynamically. Agents request resources, receive payment requirements, authorize via signatures, and settle—supporting diverse methods like stablecoins on Tempo, credit cards via Stripe/Visa, and Bitcoin Lightning via Lightspark. MPP introduces "sessions" for efficiency: an opening transaction establishes credit, followed by unlimited off-chain micropayments settled in one final on-chain tx. This collapses high-frequency agent interactions (e.g., API calls) into minimal blockchain usage, reducing latency and costs. Payment-method agnostic design allows seamless integration across fiat/crypto rails, with client-side proofs for privacy. Deployed on Tempo mainnet (Mar 2026), it's rapidly adopted for agent commerce, with SDKs/specs at mpp.dev.

Machine Payments Protocol integrated with Uniswap, adding Tempo support.