Google taps crypto giants on AI payment protocol extension

Google is working with Coinbase, the Ethereum Foundation, and MetaMask on a dedicated extension for its new protocol, specifically to accelerate and standardize agent-based crypto and stablecoin payments.

According to an announcement on September 16, the tech giant has formally launched its Agent Payments Protocol, or AP2, an open framework developed with more than 60 partners, including Mastercard, PayPal, and American Express.

Notably, alongside this broad consortium, Google revealed a targeted collaboration with key Web3 entities to build the “A2A x402 extension,” a production-ready solution designed to natively integrate cryptocurrency payments into the protocol’s core functionality from the outset.

Why Google says a protocol was needed

Google framed AP2 as a response to a structural gap in today’s payments infrastructure. Current payment infrastructure operates on a key assumption: a human is directly at the controls, clicking a “buy” button. The rise of autonomous AI agents shatters that premise, creating critical problems that existing systems cannot solve.

Google identified these gaps as authorization, authenticity, and accountability, with AP2 proposed as the answer. Per the announcement, the protocol’s solution hinges on cryptographically signed digital contracts called “Mandates.” These tamper-proof documents create a verifiable chain of evidence from a user’s initial command to the final payment.

In a real-time scenario, a user might ask an agent to find white running shoes, creating an “Intent Mandate.” After the agent presents options, the user’s approval signs a “Cart Mandate,” locking in the exact items and price. For delegated tasks, like buying concert tickets the moment they go on sale, a user signs a detailed upfront mandate with specific rules.

Google said this mechanism allows the agent to autonomously generate and execute a Cart Mandate once those precise conditions are met, with the entire sequence forging a non-repudiable audit trail and directly addressing the core questions of trust.

New commerce experiences and crypto integration

Google’s announcement illustrated a future where a customer could instruct an agent to find a specific winter jacket in green, even at a 20% premium, with the AI executing the purchase automatically upon discovery. The protocol also allows for complex, coordinated tasks, such as an agent simultaneously booking a flight and a hotel within a set total budget after negotiating with multiple travel platforms.

Alongside the general release, Google announced the A2A x402 extension, developed with Coinbase, the Ethereum Foundation, and MetaMask. This addition adapts the AP2 framework to natively support stablecoins and other digital assets, embedding Web3 rails into the protocol. Other crypto-native firms like Mysten Labs, Crossmint, BVNK, and Lightspark have also endorsed the protocol, highlighting the industry’s consensus on the need for such a standard.

Erik Reppel, Head of Engineering at Coinbase Developer Platform, framed the development as a significant maturation for the space. He noted that “x402 and AP2 show that agent-to-agent payments aren’t just an experiment anymore, they’re becoming part of how developers actually build.”

He characterized the crypto ecosystem as a “natural playground” for agents to begin transacting, suggesting that this integration is a logical step in the evolution of both AI and crypto infrastructure.