Building on Google's Agent Payment Protocol (AP2)

Matt Venables

Google just announced the Agent Payments Protocol (AP2), and we couldn't be more excited. It's validating to see our partners at Google arrive at many of the same conclusions we have about the future of agent-driven commerce – some of which we document in the open source Agent Commerce Kit (ACK). We continue to build our own financial agents on top of this foundation every day.

Let's dive into AP2, what we like about it, and where we see opportunities to extend the foundation.

A Solid Foundation

AP2 gets the fundamentals right: cryptographic signatures, verifiable credentials, and the need for trust infrastructure in agent-to-agent transactions. This validates several core principles we champion:

Cryptographic identity is essential: AP2 recognizes that agents need cryptographically verifiable identities to operate in commerce. This isn't only about preventing fraud, it's about creating accountability in autonomous systems.

Verifiable Credentials fit agentic workflows: Throughout their specification, AP2 emphasizes the use of Verifiable Credentials as the mechanism for establishing trust. This aligns with our conviction that signed digital credentials will become the backbone of agent commerce.

Structured payment flows should be transparent, observable, and auditable: AP2's mandate system (Intent Mandate → Cart Mandate → Payment Mandate) creates clear, auditable transaction flows that provide transparency and enable dispute resolution.

Agentic payments should follow open interoperable standards: We are committed to building solutions based on open standards rather than proprietary vendor-specific protocols. Agentic commerce should be accessible, extensible, avoid vendor lock-in, and benefit from broad industry collaboration.

Evolving AP2

While we love AP2's direction, we see opportunities to build on it to provide additional features we need. For example:

1. Identity: Chains of Trust

AP2 introduces the concept of "manually curated allow lists of approved agents," but doesn't describe identity verification mechanisms.

Patterns such as ACK-ID extend and augment the base concept with verifiable chains of trust which cryptographically tie agents to their accountable human or organizational owners. Rather than relying on static lists, this enables real-time identity verification with the legal compliance frameworks that enterprises need today.

2. Beyond One-Time Purchases: The Power of Receipts

As it stands today, AP2's mandates are transaction-specific and ephemeral—perfect for one-time shopping cart purchases. This is because they are designed for a single, auditable purchase flow, which is a great starting point. But agents can support richer commerce patterns by introducing a Verifiable Credential representing a “Receipt.”

A Receipt system enables persistent, reusable Verifiable Credentials that prove payment history. This unlocks:

  • Subscriptions: Pay once, access repeatedly over a set timeframe or number of uses
  • Out-of-Band Payments: Payments that happen outside the immediate browser session, enabling asynchronous agent commerce
  • Cryptographic Dispute Resolution: When payment is charged but resources aren't delivered, clients have cryptographic proof for recourse
  • Cross-Platform Recognition: Receipts work across different services and platforms

How We Will Use AP2

AP2 validates our view that the industry benefits from cryptographic trust, verifiable credentials, and structured agent commerce protocols.

Here are a few ways we plan to incorporate AP2 into our work:

AP2-Compatible Extensions to our frameworks, including ACK: We are building support for AP2's mandate formats while extending them with identity trust chains, out-of-band payments, and Receipt capabilities.

Identity Layer Integration: AP2's "credential provider" role creates opportunities for specialization. ACK-ID serves as an identity layer that plugs into AP2's framework while providing the identity verification the ecosystem needs.

Multi-Rail Payment Facilitation: ACK's Payment Service architecture can serve as an AP2 and x402-compatible payment facilitator while providing the additional capability to route payments across multiple rails based on optimization criteria.

The Big Picture

Agent commerce requires new infrastructure. Agents aren't just automated versions of human users—they operate at different scales, with different trust models, and with different economic patterns. Google's AP2 is a step forward for the space and helps establish de facto standards.

Together, we're building the foundational infrastructure for a new kind of economy: An economy where agents establish identity, operate within guardrails, prove capabilities, access resources, compensate participants, and create value and spread global prosperity in ways never before possible.

Interested in building the future of agent commerce? Check out our open-source documentation