AP2 vs the Agentic Commerce Protocol
AP2, the Agent Payments Protocol published by Google, focuses on authorisation: signed mandates that record what a user approved, usable with any payment method. ACP, the Agentic Commerce Protocol published by OpenAI and Stripe, focuses on checkout: how an agent and a merchant complete an order and pass a delegated payment credential. They address overlapping but different stages.
What each protocol is for
AP2, the Agent Payments Protocol. Published by Google in 2025 with a broad group of payments and technology partners. Its central problem is accountability: when an agent pays, how does every party know the user actually authorised that purchase? AP2's answer is mandates, cryptographically signed records of user intent. An intent mandate captures instructions for a task the agent performs without the user present, including limits. A cart mandate captures the user's approval of a specific set of items and price. These travel with the transaction so merchants and payment providers can verify authorisation. AP2 is designed to work with agent communication protocols such as Agent2Agent and MCP, and to be agnostic about payment method, including cards, bank transfers, and stablecoins, with an extension for x402 developed for crypto payments.
ACP, the Agentic Commerce Protocol. Published as open source by OpenAI and Stripe in 2025, and used for purchases made inside ChatGPT. Its central problem is checkout: how an agent presents products, creates and updates an order, and completes payment with a merchant that remains the merchant of record. Payment uses a delegated payment specification, in which a scoped payment credential is passed to the merchant for a specific purchase, with Stripe's shared payment token as the first implementation. The specification is intended to work with other processors as well.
Where they overlap and where they do not
They overlap on the idea that an agent needs a bounded, verifiable way to pay on a user's behalf. ACP bounds the payment credential to a purchase; AP2 bounds the authorisation through mandates.
They differ in the stage they emphasise. ACP specifies the merchant-facing checkout conversation in detail. AP2 specifies the evidence of consent in detail and leaves more of the checkout mechanics to the systems that carry it.
Neither moves money. Settlement still happens on a card network, a bank rail, or a blockchain. A stablecoin settlement protocol such as x402 operates at that layer, which is why AP2 has an x402 extension rather than replacing it.
Using both is plausible. A system could use an ACP-style checkout with a merchant while attaching AP2-style mandates as evidence of authorisation, and settle through whichever rail the merchant accepts. How cleanly they compose depends on how both specifications evolve.
What this means for agent builders
Whichever protocol a merchant supports, the agent still needs a payment method it cannot misuse. Bounded credentials, whether a delegated card token or a session-key limited stablecoin float, are the common requirement. CryptoCadet provides the second: non-custodial USDC on Base with session-key bounded float.
| Dimension | AP2 | ACP |
|---|---|---|
| Published by | Google, with partners | OpenAI and Stripe |
| Main focus | Proof of user authorisation | Agent to merchant checkout |
| Core artefact | Signed intent and cart mandates | Checkout session and delegated payment credential |
| Payment methods | Designed to be method agnostic, with an x402 extension | Designed to be processor agnostic, first built on Stripe |
| Merchant role | Verifies mandates from the agent | Remains merchant of record, runs checkout |
| Relation to agent protocols | Works with Agent2Agent and MCP | Integrates through merchant checkout endpoints |
| Moves funds itself | No | No |
Frequently asked questions
- What is the difference between AP2 and ACP?
- AP2, from Google, standardises proof of what a user authorised using signed mandates that travel with a purchase. ACP, from OpenAI and Stripe, standardises the checkout exchange between an agent and a merchant, including passing a delegated payment credential. They emphasise different stages of an agent purchase.
- What is a mandate in AP2?
- A cryptographically signed record of user intent. An intent mandate captures instructions and limits for a task performed without the user present, and a cart mandate captures approval of specific items and price. Merchants and payment providers can verify these to confirm the purchase was authorised.
- Do AP2 or ACP support stablecoin payments?
- AP2 is designed to be payment method agnostic and has an extension for x402, which settles stablecoin payments. ACP's delegated payment design was first implemented with Stripe and is intended to work with other processors. Settlement itself happens on the underlying rail in both cases.
- Can AP2 and ACP be used together?
- Plausibly. A system could run an ACP-style checkout with a merchant, attach AP2-style mandates as evidence of authorisation, and settle on whichever rail the merchant accepts. Both specifications are young and changing, so check current versions before relying on how they compose.