Google announced on 16 September 2025 the launch of the Agent Payments Protocol (AP2), the first open-source payment protocol designed specifically for autonomous AI agents, enabling them to transact using stablecoins and other digital assets. The protocol was developed in collaboration with over 60 leading payments and technology companies, including American Express, Mastercard, PayPal, Coinbase, Revolut, Salesforce, and Worldpay.
AP2 addresses three fundamental challenges: authorisation, proving that a user granted an AI agent specific authority to make a particular purchase; authenticity, ensuring a merchant can verify that an agent's request accurately reflects the user's true intent; and accountability, establishing responsibility when fraudulent or incorrect transactions occur. The protocol's core mechanism relies on Mandates, tamper-proof, cryptographically signed digital contracts verified through Verifiable Credentials, creating an auditable trail from the user's original request to the final payment. To support the Web3 ecosystem, Google launched the A2A x402 extension in partnership with Coinbase, the Ethereum Foundation, and MetaMask, specifically designed for agent-based digital asset payments. Erik Reppel, Head of Engineering at Coinbase Developer Platform, stated that agent-to-agent payments are no longer just an experiment but are becoming part of how developers actually build. According to Forbes, active stablecoin wallets surged from 19.6 million to over 30 million in one year, representing 53% growth, and AP2 could position stablecoins as the default currency for AI-driven systems. While PayPal, Visa, and Mastercard have previously experimented with crypto payment solutions, AP2 is the first protocol built natively with stablecoin support specifically for AI agents.
AP2 fundamentally challenges the assumption underlying current payment systems that a human clicks the buy button, opening a new era in the AI agent economy where stablecoins could serve as the lingua franca for machine-to-machine transactions. Google has published the full technical specification and reference implementations in a public GitHub repository and encourages industry stakeholders to contribute to the evolving standard, while regulatory, liability, and consumer protection questions remain to be resolved.
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