Ap2 Protocol Documentation (ap2-protocol.net)

Google’s AP2 (Agent Payments Protocol) is an open, vendor‑neutral specification to enable secure, interoperable payments initiated by AI agents. Announced as an extension of Agent2Agent (A2A) and the Model Context Protocol (MCP), AP2 tackles the unique problems agent commerce creates—authorization, authenticity, and accountability—by producing deterministic, cryptographically verifiable evidence chains instead of relying on LLM outputs. It’s backed by 60+ industry partners (Adyen, Amex, Coinbase, Mastercard, PayPal, etc.), and aims to let agents transact across cards, bank rails, wallets, stablecoins and crypto (via an A2A x402 crypto extension). Technically, AP2 uses a role‑based architecture (users, user/merchant agents, credential providers, merchant endpoints, processors, issuers) and centers on Verifiable Credentials (VCs): Cart Authorizations, User‑Signed Intent Authorizations, and Payment Authorizations. Flows support human‑present (real‑time cart approval) and human‑absent (pre‑signed intent with limits) scenarios, preserve existing fraud/risk tools (3DS2/OTP), and enable evidence‑based dispute resolution for networks and issuers. Developers can access specs and reference code on GitHub, use Google’s ADK or other agent frameworks, and expect phased rollouts (V0.1 core use cases → V1.x push payments and richer MCP integrations), opening interoperable, auditable agent commerce for the AI ecosystem.