The Agent Payments Protocol (AP2) is an open protocol from Google for payments that AI agents make on behalf of users. Google announced it on September 16, 2025, with more than 60 partners from payments and retail. The protocol is meant to work across payment types, including cards, stablecoins and real-time bank transfers.
At a glance
- Publisher
- Google; standardisation continues in FIDO Alliance working groups
- Connects
- AI agents, merchants and payment providers for payments on behalf of users
- Status
- v0.2 (release of 2026-04-28)
- License
- Apache 2.0
- Specification
- AP2: Agent Payments Protocol
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How does AP2 work?
AP2 is built around mandates, signed records of what a user has authorized an agent to do. Google ties trust to three questions: was the agent authorized, does the request reflect what the user wants, and who is accountable if something goes wrong. The signed records let the parties trace later who approved what.
According to ap2-protocol.org, Google has donated AP2 to the FIDO Alliance, where standardization continues in dedicated working groups. AP2 is designed as an extension of the Agent2Agent protocol and MCP. The Universal Commerce Protocol (UCP) lists AP2 as a compatible payment layer.
Mandates
AP2 treats mandates as verifiable digital credentials, tamper-evident objects that are chained into an audit trail. Merchants and payment providers check them to confirm that a transaction matches the user’s instructions. Version 0.2 of the specification defines two types:
- Checkout Mandate: the items and purchase details agreed between agent and merchant. It is shared with the merchant.
- Payment Mandate: authorization to pay with a specific payment instrument. It is shared with the credential provider, the networks and the merchant’s payment processor.
Each type has an open stage with the user’s constraints, such as a budget or allowed instruments, and a closed stage bound to one finalized checkout and amount. Google’s September 2025 announcement used different names, the Intent Mandate for the user’s request and rules and the Cart Mandate for the exact items and price.
| Protocol | Publisher | Connects | Status and version |
|---|---|---|---|
| MCP (Model Context Protocol) | by Anthropic, since 2025-12-09 at the Agentic AI Foundation (Linux Foundation) | AI applications with servers that provide data, tools and prompts | current version 2026-07-28 |
| A2A (Agent2Agent) | by Google, donated to the Linux Foundation; joining the Agentic AI Foundation announced on 2026-08-27 | AI agents from different vendors with each other | specification 1.0 (release v1.0.1 of 2026-05-28) |
| ACP (Agentic Commerce Protocol) | OpenAI and Stripe | buyers and their AI agents with businesses and payment providers | beta, current version 2026-04-17 |
| AP2 (Agent Payments Protocol) (this term) | Google; standardisation continues in FIDO Alliance working groups | AI agents, merchants and payment providers for payments on behalf of users | v0.2 (release of 2026-04-28) |
| UCP (Universal Commerce Protocol) | Google with commerce partners (incl. Shopify, Etsy, Wayfair, Target, Walmart) | platforms and AI agents with businesses (profile at /.) | stable, version 2026-08-25 |
| WebMCP | W3C Web Machine Learning Community Group (editors from Microsoft and Google) | websites with AI agents in the browser | draft (Draft Community Group Report of 2026-10-02), not a W3C standard; origin trial in Chrome from version 149 |
| NLWeb | Microsoft (announced 2025-05-19), open source under the MIT licence | websites (Schema.org and RSS content) with users and AI agents; every instance is an MCP server | open-source project without a published version number |
Versions and status as stated in each specification or on the publisher's site, checked on 8 October 2026. These protocols change quickly. MCP, ACP and UCP use date-based versions (YYYY-MM-DD), A2A and AP2 use version numbers. Sources: Model Context Protocol: Specification 2026-07-28; Model Context Protocol: Versioning; Anthropic: Donating the Model Context Protocol and establishing the Agentic AI Foundation (2025-12-09); A2A Protocol: Specification; A2A: A new chapter for A2A, joining the Agentic AI Foundation (2026-08-27); A2A releases (GitHub); Agentic Commerce Protocol (GitHub); AP2: Agent Payments Protocol; AP2 releases (GitHub); Universal Commerce Protocol: Specification overview (2026-08-25); Universal Commerce Protocol; WebMCP: Draft Community Group Report (W3C Web Machine Learning CG); Chrome for Developers: WebMCP (updated 2026-10-07); Microsoft: Introducing NLWeb (2025-05-19); NLWeb (GitHub). Last checked: .
Example
A shopper tells an agent to buy green running shoes for up to $130. That limit sits in an open mandate. When the agent finds an offer, a closed mandate fixes the exact item and price, and only then is payment released. If a dispute comes up later, the signed mandates show what the shopper allowed.
Common mistakes
- Using the 2025 mandate names. The September 2025 announcement spoke of the Intent Mandate and the Cart Mandate. Specification v0.2 uses the Checkout Mandate and the Payment Mandate.
- Confusing AP2 with a payment service. The protocol records what a user has authorized. Payment providers process the payment itself.
FAQ
What does AP2 stand for? Agent Payments Protocol.
Who created AP2? Google, announced with more than 60 partners. Google maintains the public repository.
What is an AP2 mandate? A signed credential that records what a user allowed an agent to buy and pay. See the Mandates section above.
Does AP2 prevent misuse? The protocol defines proofs and roles. How keys, refunds and disputes are handled depends on each implementation.
Sources
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