AP2 — Agent Payments Protocol (Google)

Maintainer: Google · Repo: google-agentic-commerce/AP2 · Status: Draft / preview

This page is a working draft. Verify all claims against the latest Google docs at the AP2 repo before quoting — AP2 is moving quickly and Google’s published materials are the canonical source.

AP2 is Google’s Agent Payments Protocol. Unlike ACP and UCP, which describe full commerce surfaces (cart, checkout, order), AP2 is intentionally narrower: it defines how an agent proves it is authorized to pay on behalf of a user, and how that authorization travels with a transaction.

Core concept — mandates

The central artifact in AP2 is a mandate: a signed, verifiable credential that says “this agent may spend up to $X with merchant Y, valid until time Z.” The mandate travels with each transaction; merchants and payment processors verify it against the issuer’s public key (typically the user’s wallet, identity provider, or device).

This is a strict superset of the bearer-token model used by ACP and complementary to the per-request HTTP signing in UCP. A mandate authorizes intent; an RFC 9421 signature authorizes this specific request.

Capabilities (current public surface)

Mandate issuance — sample agents demonstrate mandate creation
Mandate verification — reference verifier for issuer signatures
A2A transport — primary surface; AP2 messages flow between Google Agent Builder agents
MCP exposure — available through Google Agent Builder

What’s not in AP2: cart semantics, catalog, refunds, disputes. AP2 expects to compose underneath a commerce protocol (ACP or UCP), supplying the payment-authorization layer.

Integration sketch

TODO: produce a verified sketch from the AP2 sample agents in google-agentic-commerce/AP2. The pseudo-shape is:


1. User issues mandate → signed VC stored in agent wallet
2. Agent presents mandate alongside commerce request
3. Merchant / processor verifies mandate signature against issuer key
4. Merchant settles via its existing payment rail (Stripe, x402, etc.)

xpay✦ engagement

No active xpay✦ contributions to AP2 as of 2026-05-15. The mandate model is interesting as a possible auth mode for both ACP and UCP — see the comparison page for that discussion.