Agentic Commerce - The Future of AI Shopping: Understanding Google's AP2 and OpenAI's ACP

Today I want to talk about something really exciting happening in AI right now: AI agents that can actually buy things for you.

Two major protocols were announced in September 2025 — Google’s Agent Payments Protocol (AP2) and OpenAI’s Agentic Commerce Protocol (ACP). Both aim to solve the same fundamental problem but take very different approaches. Let’s explore what’s happening and why it matters.

Why This Matters

Think about how you shop online today. You search for something, compare options, add items to a cart, enter your payment details, and click buy. Every step assumes you are there clicking buttons.

But what if your AI assistant could handle all of this for you? Imagine saying: “Find me running shoes under $100 that are good for marathons and buy them when you find a great deal.” You go about your day while the AI searches, compares, negotiates, and completes the purchase when conditions are right.

This concept is called agentic commerce, and it has the potential to transform how we shop online. The challenge is that our current payment infrastructure was designed for humans, not AI agents. When an AI makes a purchase, several critical questions arise:

• Authorization: How do we prove you actually approved the purchase?

• Authenticity: How does a merchant know the AI isn’t hallucinating or making mistakes?

• Accountability: If something goes wrong, who is responsible?

Both Google and OpenAI recognised these challenges and developed protocols designed to solve them.

Google’s AP2: Building Trust Through Cryptographic Proof

Google’s Agent Payments Protocol (AP2) launched with support from more than 60 organisations including Mastercard, American Express, PayPal, Salesforce, and other major technology and financial companies. AP2 aims to create a universal framework that allows AI agents to securely initiate and complete payments across platforms.

How AP2 Works: The Mandate System

At the core of AP2 is a concept called a Mandate. These are cryptographically signed digital instructions that prove exactly what a user authorised an AI agent to do.

Think of it like giving someone a notarised letter specifying what they are allowed to buy and under what conditions. The instructions cannot be altered, and every step of the process can be verified.

AP2 uses two types of mandates:

• Intent Mandate: Defines the goal, such as finding a bicycle under $500.

• Cart Mandate: Confirms the final purchase once a specific item has been selected.

For fully automated purchases, the Intent Mandate can include rules such as maximum price limits, timing constraints, or vendor restrictions.

What Makes AP2 Unique

• Payment agnostic: Supports cards, bank transfers, and digital currencies.

• Broad ecosystem: Backed by dozens of financial institutions and technology providers.

• Cryptographic audit trails: Every transaction has verifiable proof connecting the original request to the final payment.

Typical Use Cases for AP2

• Booking travel packages within a specific budget

• Enterprise procurement and automated inventory replenishment

• Subscription management across multiple platforms

• Time-sensitive purchases such as ticket sales

OpenAI’s ACP: Merchant-First, Rapid Adoption

Shortly after AP2 was announced, OpenAI and Stripe released the Agentic Commerce Protocol (ACP) and introduced Instant Checkout in ChatGPT. Unlike AP2, ACP is already live and being used by real consumers.

Rather than building a large industry standard first, ACP focuses on enabling businesses to support AI-driven purchases using their existing commerce systems.

How ACP Works

When a user completes a purchase inside ChatGPT, the order information is passed to the merchant using ACP. The merchant remains fully responsible for processing the payment, calculating taxes, and fulfilling the order.

For merchants already using Stripe, enabling agentic checkout can be as simple as adding a single line of code.

What Makes ACP Unique

• Fast time to market: Already live in ChatGPT.

• Low integration friction: Works with existing commerce platforms.

• Merchant control: Businesses remain the merchant of record.

• Secure tokenised payments: Payments are authorised only for specific merchants and amounts.

Typical Use Cases for ACP

• In-conversation shopping within ChatGPT

• Digital product purchases and subscriptions

• Personalised product recommendations

• Simple single-item purchases

At the moment ACP supports single-item purchases, but future updates are expected to introduce multi-item carts and broader global availability.

Key Differences Between AP2 and ACP

Both protocols aim to enable AI-driven commerce, but their strategies differ significantly.

AP2 philosophy: Build a universal, secure infrastructure for agent-driven payments.

ACP philosophy: Make it easy for businesses to start selling through AI immediately.

AP2 ecosystem: Backed by dozens of organisations aiming to become a universal industry standard.

ACP ecosystem: Built by OpenAI and Stripe to accelerate adoption through ChatGPT.

Security approach: AP2 focuses on cryptographic mandates and verifiable credentials, while ACP emphasises merchant responsibility and tokenised payments.

Market status: AP2 is still in the specification and adoption stage, while ACP is already operational.

Which Approach Will Win?

In reality, both approaches may succeed and even complement each other.

AP2 could become the universal infrastructure layer for agent-driven transactions across industries, especially where compliance and auditability are critical.

ACP focuses on immediate usability and merchant adoption, allowing businesses to begin experimenting with agentic commerce today.

What This Means for Businesses and Consumers

For developers and businesses, ACP offers a quick entry point into AI-driven commerce, while AP2 may become the long-term infrastructure for more complex autonomous transactions.

For consumers, these technologies will eventually allow AI assistants to research, compare, and purchase products automatically while still keeping users in control of final decisions.

The Bigger Picture

The most exciting part of this shift isn’t just new payment protocols. It’s the emergence of AI agents that can truly act on our behalf — researching options, negotiating deals, and completing transactions.

Agentic commerce is still in its early stages, but protocols like AP2 and ACP are laying the foundation for a future where AI doesn’t just answer questions. It helps us make and execute decisions in the real economy.