AP2 (Agent Payments Protocol)
Category
AP2 is a protocol for agent-initiated payments introduced by Google, built around a chain of mandates that carry proof of what a user authorized. It aims to give a payment recipient cryptographic evidence that an agent was permitted to transact on a principal's behalf.
How it works
Authority is expressed as a chain: an intent mandate captures what the user asked for, a cart mandate captures what the agent assembled, and a payment mandate carries the instruction. Each is signed, so a recipient can verify the agent acted within granted authority. The chain proves permission; it does not describe what the transaction means to either party's books.
Example
Northwind's mandate — $5,000, market-data APIs, March, one agent — expressed as AP2 artifacts, gives each vendor verifiable evidence the agent was authorized. It does not tell Northwind's controller which expense account the charge belongs in or which period it falls into.
Common questions
What does AP2 prove?
That a specific agent held specific authority from a specific principal at the time of the transaction. That is an authorization fact, not an accounting fact.
How does AP2 relate to x402?
They solve different problems and can coexist. AP2 carries proof of authority. x402 carries the payment exchange over HTTP.