Deep Dive into Machine Payments Protocol (MPP): Resurrecting HTTP 402 for the AI Agent Era

Removes the need for CAPTCHAs and manual checkout flows. Account-less Payments: Enables autonomous, on-the-spot payments without prior sign-up or OAuth. Agnostic Design: Compatible with various payment rails like Tempo (stablecoins), Stripe (cards), and Lightning (BTC). 2. Core Mechanism: Challenge-Credential-Receipt MPP communication consists of the following sequence: Protocol overview | MPP Standardizing HTTP 402 for machine-to-machine payments mpp.de Challenges: The server specifies "how much, in what currency, and via which payment rail" i.