Selling to AI: The Complete Guide to Agentic Commerce

For 30 years, checkout has been a page. A form with fields for name, address, credit card number. Whether it was Amazon's one-click patent or Apple Pay's fingerprint, the innovation was always about making that form faster to get through.

The form itself never went away. Now it is.

This is the final article in a five-part series on optimizing websites for the agentic web. Part 1 covered the evolution from SEO to AAIO. Part 2 explained how to get your content cited in AI responses. Part 3 mapped the protocols forming the infrastructure layer. Part 4 got technical with how AI agents perceive your website. This article covers the commerce layer: how AI agents find products, complete purchases, and handle payments without ever loading a checkout page.

In September 2025, Stripe and OpenAI launched Instant Checkout inside ChatGPT. In January 2026, Google and Shopify unveiled the Universal Commerce Protocol at the National Retail Federation conference. Two open standards. Two competing visions for the same shift: checkout becoming a protocol, not a page.

Throughout this article, we draw exclusively from official documentation, research papers, and announcements from the companies building this infrastructure.

Updated September 14, 2026: Added UCP's third release v2026-08-25 (Loyalty, Local Fulfilment, Catalog Data Quality, Fractional Quantity Units, OAuth token exchange) and its expansion into Food Ordering and Lodging verticals, both presented by Google at the W3C and GS1 workshop in Zurich on September 8. Added Shopify adopting that release on September 4, deprecating its own Storefront MCP cart tools for UCP Cart MCP on June 24, and launching WebMCP on every Liquid storefront on August 5. Added the Merchant Advisory Group's liability waterfall and payment-routing demands from the same workshop. Corrected x402's governance to the x402 Foundation, and noted that Stripe's Shared Payment Tokens remain a preview product in 34 countries.

Updated May 13, 2026: Added Stripe Projects launch (April 30) as the second commerce category for infrastructure procurement, AP2 v0.2 with FIDO Alliance donation (April 28), UCP April 8 release expanding partners past twenty, ChatGPT Instant Checkout sunset (March 5) and pivot to retailer-operated ChatGPT Apps, Amazon v. Perplexity heading to Ninth Circuit oral arguments June 11, and Adobe Q2 2026 data showing AI-referred traffic now converts 42% better than non-AI.

In This Series

1. From SEO and CRO to 'AAIO': Why Your Website Needs to Speak to Machines
2. Answer Engine Optimization: How to Get Your Content Into AI Responses
3. MCP, A2A, WebMCP, NLWeb, and AGENTS.md: The Standards Powering the Agentic Web
4. How AI Agents See Your Website (And How to Build for Them)
5. Selling to AI: The Complete Guide to Agentic Commerce (You are here)

Contents

• How We Got Here
• Checkout Is No Longer a Page
• The Agentic Commerce Protocol
• The Universal Commerce Protocol
• Stripe Projects: The Second Commerce Category
• The Trust Problem: Payments Without People
• The Legal Test: Amazon v. Perplexity
• Who's Already Selling to AI
• The Market
• How to Get Started
• Key Takeaways

How We Got Here

Every generation of commerce technology has solved the same problem: reducing the friction between "I want something" and "I have it." Agentic commerce is not a break from this pattern. It's the pattern's logical conclusion.

1994: The first online purchase. On August 11, 1994, Phil Brandenberger used his credit card to buy Sting's Ten Summoner's Tales CD for $12.48 from a website called NetMarket. The New York Times covered it the next day. NetMarket's 21-year-old CEO, Daniel Kohn, told the paper: "Even if the N.S.A. was listening in, they couldn't get his credit card number." Netscape's SSL protocol, released that same year, made it possible.

The friction removed: you no longer had to go to a physical store.

Late 1990s: Comparison shopping. Within a few years, websites like BizRate (1996), mySimon (1998), and PriceGrabber (1999) let buyers see prices across multiple merchants instantly. Google entered the space in 2002 with Froogle, later renamed Google Product Search in 2007, then Google Shopping in 2012.

The friction removed: you no longer had to visit each store to compare.

1998: The store adapts to you. Amazon deployed item-to-item collaborative filtering at scale, the algorithm behind "customers who bought this also bought." Greg Linden, Brent Smith, and Jeremy York published the underlying research in IEEE Internet Computing in 2003. In 2017, the journal named it the best paper in its 20-year history.

The friction removed: you no longer had to know exactly what you wanted.

2015: Commerce moves into conversations. Chris Messina, then Developer Experience Lead at Uber, coined the term "conversational commerce" in a January 2015 Medium post, describing "delivering convenience, personalization, and decision support while people are on the go." In April 2016, Mark Zuckerberg launched the Facebook Messenger Platform, declaring: "I've never met anyone who likes calling a business." Meanwhile, in China, WeChat had already proved the model. Its Mini Programs, launched January 2017, generated 800 billion yuan (~$115 billion) in transactions by 2019.

The friction removed: you no longer had to open a store's website.

2014-2023: Voice and social commerce. Amazon Echo launched in November 2014, promising you could buy things without a screen. The promise was mostly unfulfilled. Social commerce had better luck: TikTok Shop, launched in the US in September 2023, reached $33.2 billion in global sales by 2024. Content became the storefront.

The friction removed: purchase intent was created inside the feed, not searched for.

2024: AI starts shopping for you. Within months, every major platform launched AI shopping features. Amazon introduced Rufus in February, a conversational assistant trained on its product catalog. Google rebuilt Shopping with AI in October, drawing on 50 billion product listings. Perplexity launched "Buy with Pro" in November, turning a search engine into a store.

The friction removed: AI did the research, comparison, and recommendation for you.

2025: The buyer disappears. In January, OpenAI launched Operator, an agent that navigated websites, filled forms, and completed purchases autonomously. In May, Google announced "Buy for Me" at I/O 2025. In September, Instant Checkout went live in ChatGPT.

The friction removed: the last one. The human no longer needs to be there for the transaction to happen.

Each of these shifts was about the same thing: removing one more step between wanting and having. Agentic commerce removes the final step: doing it yourself.

Checkout Is No Longer a Page

Here's the shift in one sentence: in traditional commerce, the seller builds the checkout experience. In agentic commerce, the agent does.

When you buy something on a website today, you interact with the merchant's checkout page. They designed the form, they chose the layout, they control the flow. You fill in your details, click "Buy," and the payment processes.

In agentic commerce, the AI agent presents the checkout information within its own interface. ChatGPT shows you the product, the price, the shipping options, within the chat. You confirm. The agent handles the rest. The merchant never renders a page. They receive an API call.

Stripe's agentic commerce guide puts it directly: "The parts of commerce that used to be user experience problems are becoming protocol problems." Instead of optimizing button colors and form layouts, merchants are defining API endpoints and product feeds. Discovery, comparison, and checkout are all handled by the agent. The merchant's job shifts to supplying structured product data and processing the order.

Emily Glassberg Sands, Stripe's Head of Information and Data Science, framed the broader implications: "Agents don't just change who's at the checkout. They change who's doing the searching, the deciding, the trusting. All of it."

I discussed this with Jes Scholz, who ran digital across 140+ e-commerce brands at Ringier, on the podcast. Her experience was clear: agents browse in text mode, and if they can't parse your site cleanly, they leave. No second chances.

This isn't theoretical. Multiple agentic commerce surfaces are live as of September 2026. Shopify's Agentic Storefronts are active by default for eligible merchants, syndicating products to ChatGPT, Google AI Mode, Microsoft Copilot, and Perplexity simultaneously. Perplexity launched Instant Buy with PayPal in November 2025, allowing purchases directly within the chat interface with merchants like Wayfair, Abercrombie & Fitch, and thousands more via BigCommerce and Wix. Microsoft launched Copilot Checkout on January 8, 2026, anchored on PayPal as the payment processor and supporting Shopify, Stripe, and Etsy at launch.

The ChatGPT story has a wrinkle. OpenAI launched Instant Checkout in September 2025, available to US users on Free, Plus, and Pro plans. Etsy, Instacart, and Walmart were among the early merchants processing orders through it. On March 5, 2026, OpenAI sunset Instant Checkout after roughly 30 Shopify merchants had integrated. The retired feature was replaced with "ChatGPT Apps," where retailers run their own in-chat experiences and handle the transaction inside their own surface. Walmart's Sparky, Etsy, Target, Instacart, Expedia, and Booking.com are among the launch cohort. The Agentic Commerce Protocol that powered the original Instant Checkout survives as the infrastructure layer and continues to be the cleanest path for new retailer integrations. The consumer-facing shape, inside OpenAI's product specifically, shifted from native-in-chat checkout to retailer-operated apps.

Every major AI company is moving in this direction, with different strategic bets. Anthropic confirmed in February 2026 that it was building features for "agentic commerce, where Claude acts on a user's behalf to handle a purchase or booking end to end." What has actually launched points to a B2B-merchant-operations direction more than a consumer-shopping one. Anthropic Integrations now lists Stripe, PayPal, and Square as official MCP plugins, and Anthropic announced Claude for Small Business on May 13 with PayPal, QuickBooks, HubSpot, Canva, DocuSign, Google Workspace, and Microsoft 365 packaged for small-business workflows. The framing is the merchant operating with Claude, not the consumer shopping with Claude. In June 2025, Anthropic published Project Vend, a research experiment where Claude autonomously operated a physical retail store for a month. The results were instructive: the agent performed well at supplier discovery and customer service, but sold items at a loss and hallucinated payment details. The merchant-side direction Anthropic has taken is consistent with the lessons from that experiment.

Two open protocols are making this possible. Both launched within four months of each other.

The Agentic Commerce Protocol

The Agentic Commerce Protocol (ACP) is an open standard co-developed by OpenAI and Stripe, announced September 29, 2025. Licensed under Apache 2.0, it defines how AI agents complete purchases on behalf of users.

ACP uses a four-party model: the buyer (discovers and approves), the AI agent (presents products and handles checkout UI), the merchant (processes the order and payment), and the payment service provider (handles payment credentials securely). The merchant remains the merchant of record. They process the payment, handle fulfillment, manage returns. The agent is an intermediary, not a marketplace.

The protocol defines four API endpoints:

The responsibility shift is worth spelling out:

The agent handles what the buyer sees. The seller handles what happens after they click "Buy." ACP can be implemented as either a REST API or an MCP server, connecting naturally to the protocol ecosystem covered in Part 3.

Stripe's Agentic Commerce Suite, launched December 11, 2025, makes ACP adoption practical. Ahmed Gharib, Stripe's Product Lead for Agentic Commerce, described it as "a low-code solution enabling businesses to sell across multiple AI agents via a single integration." Without it, connecting to each AI agent individually would take up to six months of bespoke engineering per platform.

The Suite has three components: product discovery (sync your catalog and Stripe distributes it to AI agents), checkout (powered by Stripe's Checkout Sessions API, handling taxes and shipping), and payments (using Shared Payment Tokens and Stripe Radar for fraud detection). Merchants connect their existing product catalog or upload directly to Stripe, then select which AI agents to sell through from the Stripe Dashboard.

The ecosystem is growing quickly. Beyond OpenAI, Stripe lists Microsoft Copilot, Anthropic, Perplexity, Vercel, and Replit as AI platform partners. On the e-commerce side, Squarespace, Wix, WooCommerce, BigCommerce, and commercetools have integrated. Salesforce announced ACP support in October 2025.

ACP expanded its scope materially in April 2026. The ACP 2026-04-17 release added Cart, Feed, Orders, Authentication, and MCP integration to the protocol surface. The release turned ACP from a checkout-only protocol into a discovery-through-fulfillment surface covering the full lifecycle: catalog reading through Feed, cart management as a separate surface from checkout, order tracking and management through Orders, and standardized authentication across the agent-merchant boundary. The earlier 2026-01-30 release added extensions, discounts, and payment handlers. Vendors building ACP support today are building against the expanded surface, not the narrow original.

The Universal Commerce Protocol

Four months after ACP launched, a different coalition unveiled a second standard.

The Universal Commerce Protocol (UCP) was co-developed by Shopify and Google, announced January 11, 2026 at the National Retail Federation conference in New York. Google CEO Sundar Pichai presented it. The co-developers include Etsy, Wayfair, Target, and Walmart. Over 20 companies endorsed it at launch, including Mastercard, Visa, Best Buy, Home Depot, Macy's, American Express, and Stripe. I broke down UCP and its strategic implications the week it launched on the podcast.

Where ACP is tightly focused on the checkout flow, UCP is designed as a full commerce standard covering discovery through post-purchase. Its architecture is modeled after TCP/IP, with three layers:

UCP is protocol-agnostic. It supports REST, MCP, A2A, and AP2 (Agent Payments Protocol, Google's standard for agent-initiated payments). ACP currently supports REST and MCP.

Discovery works through a published profile at /.well-known/ucp, similar to how A2A agents publish their capabilities at /.well-known/agent-card.json (covered in Part 3). Both agents and merchants declare their capabilities, and on each request, the system computes the intersection of what they can do together. Ashish Gupta, VP/GM of Merchant Shopping at Google, described the logic: "The shift to agentic commerce will require a shared language across the ecosystem."

The two protocols reflect different strategic positions. ACP, built by the company running the AI agent (OpenAI) and the company processing the payment (Stripe), is optimized for getting transactions through ChatGPT quickly. UCP, built by the company hosting the merchants (Shopify) and the company running search (Google), is designed for a multi-agent future where many AI platforms compete for the same shoppers.

The good news for merchants: these aren't mutually exclusive. Shopify merchants can serve both simultaneously. The same products appear in ChatGPT via ACP and in Google AI Mode via UCP. Shopify's Agentic Storefronts handle the multi-protocol complexity, syndicating catalog data across ChatGPT, Google AI Mode, Microsoft Copilot, and Perplexity from a single admin panel.

Vanessa Lee, Shopify's VP of Product, framed the company's position: "Agentic commerce has so much potential to redefine shopping and we want to make sure it can scale."

UCP has had three material releases since the January launch. On March 19, 2026, Google added an optional Cart capability to UCP, letting agents add and save multiple items per store in a single session rather than running checkout flows item by item. On April 8, 2026, Google released UCP version 2026-04-08, which expanded the endorsement list to over twenty organizations. The full roster now includes Adyen, American Express, Best Buy, Flipkart, Macy's, Mastercard, The Home Depot, Visa, Zalando, Shopify, Walmart, Target, Etsy, Wayfair, BigCommerce, PayPal, and Stripe. Geographic coverage spans North America, the EU, and the UK, with APAC rollout completing by end of Q3 2026. WooCommerce remains a notable absence from the launch and April rosters.

The third release, v2026-08-25, is the one that changes what UCP is for. It added Loyalty and Local Fulfilment as capabilities, plus Catalog Data Quality, Fulfilment Options, Fractional Quantity Units, and OAuth token exchange for account linking. Amit Handa of Google presented the release at the W3C and GS1 workshop in Zurich on September 8, 2026, alongside the project's own development figures: 500+ pull requests, 56,000+ lines of code, and 112+ unique contributors since January.

The same presentation showed UCP extending past retail entirely. Food Ordering and Lodging are now separate verticals with their own capabilities, sharing Identity Linking, Payment and Location with the shopping vertical. The ecosystem slide for that expansion names Doordash, Booking.com, Marriott, Trip.com, Amadeus, Expedia Group, Uber Eats, Toast and Hilton. A protocol announced in January as a common language for shopping now covers hotel bookings and food orders.

Shopify moved to the August release within ten days. On September 4, 2026, Shopify storefronts began advertising UCP 2026-08-25 in their discovery profiles at /.well-known/ucp, and in Shopify's words the change "doesn't require any changes to your existing integrations." Shopify says it runs these protocols in production across millions of merchants, so on its own account a very large number of storefronts gained a protocol version without their merchants doing anything.

Shopify also retired its own equivalent. On June 24, 2026, it deprecated the Storefront MCP cart tools in favour of UCP Cart MCP, moving get_cart and update_cart to a UCP-conforming endpoint at /api/ucp/mcp. Shopify co-authored UCP, so this is not deference to a rival. It is a platform that had built its own agent cart surface retiring it rather than maintaining two.

And it is running a second, different surface alongside UCP. On August 5, 2026, Shopify added WebMCP support to Liquid and Hydrogen storefronts, so a store's pages register tools an agent can call inside the browser tab the shopper is already looking at. Shopify's words: "The tools are live today on every Liquid storefront." The distinction matters if you are deciding what to build. UCP is server-side, an agent calling your store directly with no browser involved. WebMCP is in-page, for an agent driving a browser on a person's behalf. Shopify launched both within seven weeks. They answer different questions. WebMCP is covered in more depth in Part 3.

Stripe Projects: The Second Commerce Category

On April 30, 2026, Stripe launched Projects in open beta, a commerce protocol that lets AI agents create accounts, buy domains, upgrade plans, and deploy infrastructure on behalf of human owners. Cloudflare, Vercel, and Netlify launched as partners. Projects runs in parallel to ACP, with ACP handling retail commerce and Projects handling infrastructure procurement.

The split matters because the audit questions for each category are different. A retail merchant supporting ACP exposes a product catalog, handles a checkout endpoint, and ships fulfillment afterwards. An infrastructure vendor supporting Projects exposes a plan-and-resource catalog, handles a signup endpoint, provisions capability after purchase, and manages the ongoing subscription. The merchant-side instrumentation lives in different parts of the website. The user-side authorization grants are wider for Projects because the agent is buying an ongoing relationship rather than a one-time purchase.

The launch cohort signals the category Stripe is targeting first. Cloudflare, Vercel, and Netlify all sit at the developer-platform layer of cloud infrastructure: edge compute, deployment platforms, and content delivery. All three had API-first product surfaces before Projects, which is why they could add support fastest. The next ring out, plausibly, is SaaS subscriptions for non-developer audiences, then general-purpose cloud and traditional B2B SaaS.

Both Projects and ACP use Shared Payment Tokens for the agent transaction and run on the same Stripe payment rails. The shared plumbing is the reason both protocols coexist cleanly under one vendor. Read more in Stripe Projects Opens Cloud Infrastructure Buying To AI Agents.

The Trust Problem: Payments Without People

Both protocols face the same foundational challenge: how do you process a payment when the person with the credit card isn't the one at the checkout?

Traditional commerce treats credential possession as a trust signal. If you have the card number, the expiry date, and the CVV, you're probably the cardholder. Agentic commerce breaks this assumption. The agent has been authorized to act on the buyer's behalf, but it's not the buyer. As Stripe's Kevin Miller wrote in his October 2025 blog post: "Trust can't be inferred. It has to be explicitly granted, scoped, and enforced in code."

Javelin Strategy & Research, cited by Visa, describes this as the shift from "card-not-present" to "person-not-present" transactions. It's a useful framing. Card-not-present fraud was the defining challenge of e-commerce. Person-not-present fraud is the defining challenge of agentic commerce.

Shared Payment Tokens

Stripe's solution is the Shared Payment Token (SPT), a new payment primitive designed specifically for agent transactions. Here's how it works:

1. The buyer saves a payment method with the AI platform (e.g., ChatGPT)
2. When approving a purchase, the AI platform issues an SPT scoped to the specific merchant, capped at the checkout amount, with a time limit
3. The AI platform sends the SPT to the merchant via ACP
4. The merchant creates a Stripe PaymentIntent using the token
5. Stripe processes the payment, applying fraud detection in real time

One thing the list above leaves out: Shared Payment Tokens are still a preview product. Stripe's own API calls for them carry Stripe-Version: 2026-04-22.preview, the seller terms you accept are labelled stripe-agentic-commerce-seller-services-preview, and availability is 34 enumerated countries rather than "most markets" (checked at Stripe's documentation on September 14, 2026). That is more specific than most of this field manages, and it still means the primitive underneath ACP is not generally available.

The buyer's actual card details are never shared with the merchant or the agent. Each token is programmable (scoped by merchant, time, and amount), reusable across platforms, and revocable at any time. For existing Stripe merchants, enabling SPTs requires "as little as one line of code."

The Payment Networks Respond

The card networks have launched their own standards. Visa introduced the Trusted Agent Protocol in October 2025, an open framework built on HTTP Message Signatures that helps merchants distinguish legitimate AI agents from malicious bots. Developed in collaboration with Cloudflare, it has feedback from Adyen, Checkout.com, Microsoft, Shopify, Stripe, and Worldpay among others.

Mastercard launched Agent Pay in April 2025, introducing "Agentic Tokens" that build on their existing tokenization infrastructure. Each agent action uses permissions and limits defined by the consumer. US issuers were enabled in November 2025. In January 2026, Mastercard completed the first authenticated agentic transaction in APAC through Agent Pay in Australia. Banco Santander completed Europe's first live end-to-end AI-agent payment via Agent Pay in March 2026. Mastercard's enterprise tooling for agentic commerce, Agent Suite, went GA in Q2 2026 with Citi and U.S. Bank piloting.

PayPal joined the ACP ecosystem on October 28, 2025, enabling PayPal wallets for ChatGPT checkout. In early 2026, PayPal launched Agent Ready, auto-enrolling millions of existing PayPal merchants for AI-surface acceptance with no technical lift. PayPal's Store Sync surfaces inventory to Microsoft Copilot, Perplexity, Shopware, Wix, and Cymbio, and PayPal anchors the payment leg of Microsoft Copilot Checkout's launch (January 8, 2026). BigCommerce expanded its PayPal partnership in 2026 to put Store Sync directly in the app marketplace.

Google launched its own payment standard in parallel. The Agent Payments Protocol (AP2), announced September 2025, uses Verifiable Digital Credentials and a cryptographic Mandate system to create tamper-evident proof of user consent at every step of the transaction. On April 28, 2026, Google released AP2 v0.2 and donated the protocol to the FIDO Alliance for community governance. The v0.2 release added Human Not Present payments (agents executing pre-authorized transactions when the human is not on the call), Verifiable Intent through Mandates with Open and Closed states (co-developed with Mastercard, also donated to FIDO), a PaymentReceipt primitive, X402 payment-method support inside human-in-the-loop samples, and a Go SDK alongside the existing Python one. The donation surfaced a sixty-organization contributor list including Mastercard, American Express, PayPal, Adyen, Coinbase, Etsy, Forter, Intuit, JCB, Mysten Labs, Revolut, Salesforce, ServiceNow, UnionPay International, and Worldpay. AP2 is payment-agnostic, supporting credit and debit cards, real-time bank transfers, and stablecoins via the x402 extension. It is integrated directly into UCP. x402 started at Coinbase and is now governed by the x402 Foundation, the third agentic protocol to move to a foundation this year after A2A went to the Linux Foundation and MCP to the Agentic AI Foundation. The Coinbase repository is now a fork of the foundation's, so anyone still watching coinbase/x402 for changes is watching the wrong one.

The protocol-aggregation layer emerged in April. Visa launched Intelligent Commerce Connect on April 8, 2026, the first vendor-neutral on-ramp accepting agents across Trusted Agent Protocol, Mastercard's Machine Payments Protocol, ACP, and UCP simultaneously. Visa reports over one hundred ecosystem partners, thirty plus active in the Visa Intelligent Commerce sandbox, and twenty plus direct integrations. APAC and European pilots launched in early 2026, with UAE consumer pilots running through Aldar for recurring fee categories. The structural move is that one network is now positioned as the protocol-agnostic translator between commerce standards, the way Stripe positioned itself as the translator between payment methods in the 2010s.

Fraud Without Fingerprints

Traditional fraud detection relies on human behavioral signals: mouse movements, typing patterns, browsing behavior, session duration. AI agents have none of these. A legitimate agent transaction can look indistinguishable from a sophisticated bot attack.

Stripe addressed this by building what they describe as "the world's first AI foundation model for payments," a transformer-based model trained on tens of billions of transactions. The model treats each charge as a token and behavior sequences as context, ingesting signals including IPs, payment methods, geography, device characteristics, and merchant traits. When SPTs are used, Stripe Radar relays risk signals including dispute likelihood, card testing detection, and stolen card indicators to help "differentiate between high-intent agents and low-trust automated bots."

The attack surface is also novel. Researchers demonstrated in a June 2025 study that e-commerce agents are susceptible to visual prompt injection: malicious content embedded in product listings can hijack agent behavior during shopping tasks. All agents tested were vulnerable. A separate study accepted to IEEE S&P 2026 found that 13% of randomly selected e-commerce websites had already exposed their chatbot plugins to indirect prompt injection via third-party content like product reviews. And a January 2025 paper on authenticated delegation argues that for agentic commerce to function at scale, the industry needs standardized mechanisms to "explicitly delegate authority to agents, transparently identify those agents as AI, and enforce human-centered choices around security and permissions." SPTs, the Trusted Agent Protocol, and Agent Pay are all early answers to that challenge.

The concern is real on the consumer side too. 88% of consumers surveyed by Javelin are concerned that AI will be used for identity fraud, according to Visa's analysis. Building trust infrastructure that works for agent transactions is the prerequisite for agentic commerce scaling beyond early adopters.

The Regulatory Layer Is Still Behind The Protocols

The protocols are moving faster than the regulators. The EU AI Act becomes fully applicable on August 2, 2026. Agents making autonomous purchases on behalf of consumers potentially fall under high-risk classification, with fines reaching seven percent of global turnover for prohibited practices and three percent for standard violations. The Act predates agentic commerce and contains no provisions specifically written for autonomous purchasing agents, which leaves a gap in how the rules apply.

In the United States, no federal agency has published agentic-commerce-specific rulemaking. The FTC's Section 5 authority covering unfair-or-deceptive practices can reach failure to disclose AI involvement in customer-facing interactions. The SEC has not weighed in on agentic-procurement disclosure. The legal test for agent-as-visitor access rights is being decided in the courts, not in legislation. The next section covers the case that defines that test.

What merchants asked for, out loud

Almost everything above is written from the vendor side. On September 8 and 9, 2026, W3C and GS1 ran a joint workshop in Zurich on e-commerce for humans and AI agents, and the Merchant Advisory Group used its session to state what merchants need before any of this is safe to join. It is the clearest merchant-side position published so far, and it is worth reading as a checklist rather than a complaint.

Their framing of the problem is that card-not-present rules assume a human made the purchase decision and allocate fraud liability to the merchant by default unless the transaction is authenticated. An agent transaction breaks that assumption: it can be technically authorized and still disputed because the agent exceeded its delegated authority or acted on stale information. Existing rules do not cover that case, so, in their words, liability "defaults to merchants by convention rather than by control over the failure point."

Their proposal is a liability waterfall that assigns responsibility to whoever controlled the function that failed, in order: the consumer as principal where the agent stayed inside its mandate, the agent operator where it exceeded or malfunctioned, the wallet or trust provider where credential issuance or revocation failed, the processor or network where transaction handling failed, and the merchant only where the failure was inside the merchant's own systems. They also recommend a distinct "Human-Not-Present" transaction class for purchases made without real-time human confirmation.

The second demand is the one nobody else on this page is raising, and it is about money rather than trust. If an agent's credential is bound to a particular wallet, platform or processor vault, the merchant loses the practical ability to switch processors, negotiate rates, or route to the cheapest eligible network. Worse, when the agent operator or wallet picks the payment path before the transaction ever reaches merchant systems, the merchant's routing preferences can be bypassed entirely. US debit-routing rules give merchants enforceable rights here, and those rules have not been updated for agent-initiated transactions, so the protection does not clearly apply. Their point is that the protocols above are all specific about who holds the credential and silent, so far as merchants have been able to establish, about who keeps the right to route it.

The Legal Test: Amazon v. Perplexity

The first major legal test of agent-as-visitor rights in the United States is Amazon's lawsuit against Perplexity over its Comet browser. Amazon sued in late 2025, arguing that Comet's access to Amazon's logged-in pages on behalf of users violates the Computer Fraud and Abuse Act, and on March 10, 2026 a federal judge issued a preliminary injunction blocking Comet from Amazon's password-protected pages. The Ninth Circuit paused it pending appeal and heard argument on June 11.

On August 4, 2026 the panel ruled and vacated the injunction. In No. 26-1444, published and precedential, the court held that the Assistant "is a tool, not a person for statutory purposes," so "it is the user who 'accesses' Amazon's computers." The CFAA is largely off the table for an agent acting on a logged-in user's instruction.

Two caveats before you plan around it. The reasoning rests on Comet running locally on the user's device, and the court expressly reserved the case of an agent that runs on the vendor's own servers. And the panel said it was deliberately not settling the field: "We do not establish a new legal regime governing agentic AI."

The practical result for a merchant is a handoff. The court's footnote states the outcome "does not impair Amazon's ability to regulate access to Amazon.com via private terms of service for its users." So agent access is now settled by your own terms. If you want a position on agents acting for your logged-in customers, it has to be written into them, because the anti-hacking statute will not carry it. Amazon has petitioned for rehearing en banc, so this is not yet final. Read more in Amazon v. Perplexity: The CFAA Case That Decides Whether AI Agents Can Visit Your Website.

Who's Already Selling to AI

Despite the infrastructure still being built, adoption is moving fast.

AI platforms with commerce capabilities:

Merchants and brands on board:

The early adopter list reads like a mall directory. URBN (parent of Anthropologie, Free People, and Urban Outfitters), Etsy, Coach, Kate Spade, Glossier, Vuori, Spanx, SKIMS, Ashley Furniture, Revolve, and Halara are among those onboarding to Stripe's Agentic Commerce Suite. Walmart and Instacart are live on ChatGPT. Gymshark, Everlane, and Monos are live on Google AI Mode via UCP.

E-commerce platforms enabling it:

Shopify's 1 million+ US merchants are eligible for ChatGPT integration. BigCommerce, Wix, Squarespace, WooCommerce, and commercetools have integrated with Stripe's Suite. Salesforce Commerce Cloud announced ACP support in October 2025, with new Agentforce agents for merchant, buyer, and personal shopper workflows.

The Market

The market projections vary widely, which tells you how early we are. McKinsey projects $1 trillion in US retail revenue orchestrated by agents by 2030, scaling to $3-5 trillion globally. Gartner predicts 90% of B2B purchases will be handled by AI agents within three years, intermediating $15 trillion in spending by 2028. Forrester predicts that by 2026, one-third of retail marketplace projects will be deserted as answer engines steal traffic.

The consumer side is more cautious. A YouGov survey of 1,287 US adults found 65% trust AI to compare prices, but only 14% trust it to actually place an order. Among Gen Z, that number rises to 20%. The gap between "I'll let AI help me shop" and "I'll let AI buy for me" is where we are right now.

But the traffic is already there. Shopify reported that orders attributed to AI searches grew 11x since January 2025. OpenAI estimates approximately 2% of all ChatGPT queries are shopping-related, roughly 50 million shopping queries daily across a user base of 700 million weekly users.

The picture in 2026 has sharpened further. Adobe's 2026 Q2 AI Traffic Report, published April 16, 2026, found AI-referred traffic to US retailers grew 393% year-over-year in Q1 2026, peaking at 1,151% YoY in December during the holiday season. The conversion picture reversed: AI-referred traffic converted 42% better than non-AI traffic in March 2026, compared with roughly half the non-AI rate twelve months earlier. AI-driven revenue per visit is now 37% higher than non-AI revenue per visit. The pre-qualification effect that the report names is the structural reason. A visitor who clicks through from ChatGPT or Perplexity has already done the research, compared the options, and narrowed the choice inside the assistant. The click is the last step of the decision, not the first. The full data and operator implications are in Lessons Learned From Adobe's 2026 Q2 AI Traffic Report.

Academic research is starting to reveal what happens when agents do the buying. A Columbia Business School and Yale study (August 2025) introduced ACES, the first agentic e-commerce simulator, and tested six frontier models including Claude and GPT-4. They found that AI shopping agents exhibit "choice homogeneity," concentrating demand on a small number of products and showing strong position biases in how listings are ranked. The researchers warn of winner-take-all dynamics and the emergence of "AI-SEO," where sellers optimize listings specifically for agent behavior rather than human preferences. A February 2026 study on personalized product curation found that current agentic systems remain "largely insufficient" for tailored product recommendations in open-web settings. The agents are getting better at buying. They're not yet great at buying the right thing for a specific person.

The infrastructure is being built regardless of whether consumers are fully ready. When they are, the businesses that prepared will be the ones the agents can find.

How to Get Started

The good news: for most businesses, the entry point is simpler than you'd expect.

If you're on Shopify, you may already be selling to AI. Agentic Storefronts are active by default for eligible US merchants. Your products are syndicated to ChatGPT, Google AI Mode, Microsoft Copilot, and Perplexity from your existing Shopify admin. Check your dashboard for the agentic channel settings and ensure your product data (descriptions, images, categories) is clean and complete.

If you're on Stripe, enabling Shared Payment Tokens for ACP requires as little as one line of code. The Agentic Commerce Suite handles catalog syndication, checkout, and fraud detection. Connect your product catalog, select which AI agents to sell through, and you're live.

If you're on BigCommerce, Wix, Squarespace, or WooCommerce, integrations with Stripe's Suite are available. BigCommerce described the shift from "months of bespoke engineering work" per AI platform to "a single, configurable integration."

For the spoke that walks through which platform's existing integration covers your stack, see Agentic Commerce for Small Merchants.

Regardless of platform, the protocol integrations get you connected. But agents still need to find and understand your products. This is where the work from Part 2 (getting cited) and Part 4 (being agent-readable) converges with commerce.

Audit your product data. Agents parse your catalog programmatically. Every product needs:

• A descriptive, specific title ("Men's Organic Cotton Crew Neck T-Shirt, Navy" not "Blue Shirt")
• A complete description including materials, dimensions, care instructions, and use cases
• Accurate, real-time pricing and stock availability
• High-quality images with descriptive alt text
• Consistent categorization across your catalog

Add structured markup. At minimum, every product page should include Product schema with name, description, image, sku, and brand, plus nested Offer schema with price, priceCurrency, availability, and seller. If you have reviews, add AggregateRating. This is the machine-readable layer that agents parse when direct protocol integrations aren't available. I talked about this with Duane Forrester, who co-launched Schema.org while at Bing, on the podcast. His argument: consistent structured data builds what he calls "machine comfort bias," where AI systems develop a preference for sources that have proven reliable over time.

Test your agent visibility. Open ChatGPT, Perplexity, and Google AI Mode and ask them to recommend products in your category. If yours don't appear, agents can't sell them. View your product pages in reader mode or a text-based browser to see what agents see when they visit your site directly (covered in Part 4).

Track agent-driven traffic. ChatGPT appends utm_source=chatgpt.com to referral links. Perplexity and other AI platforms leave similar referral signatures. Set up segments in your analytics to isolate AI-referred visits and monitor conversion rates separately from human traffic. The numbers are small now, but 393% year-over-year growth means they won't stay small, and the traffic converts 42% better than non-AI traffic once it arrives.

Walmart CEO Doug McMillon put it directly: "For many years now, eCommerce shopping experiences have consisted of a search bar and a long list of item responses. That is about to change."

Whether it changes next quarter or next year for your business depends on whether your product data is ready when the agents come looking.

Key Takeaways

• Checkout is becoming a protocol, not a page. In agentic commerce, the AI agent handles the interface and the merchant processes the order. The retail layer has two open standards, ACP (Stripe + OpenAI) and UCP (Shopify + Google), and an infrastructure layer (Stripe Projects) for buying capabilities rather than products.

• Three protocols cover different surfaces. ACP and UCP cover retail. The ACP 2026-04-17 release expanded ACP from checkout-only to discovery-through-fulfillment. UCP has had three releases: 2026-04-08 expanded the endorsement coalition past twenty organizations, and 2026-08-25 added Loyalty and Local Fulfilment and pushed UCP beyond retail into food ordering and lodging. Stripe Projects (April 30, 2026) covers infrastructure procurement with Cloudflare, Vercel, and Netlify as launch partners.

• OpenAI Instant Checkout was retired March 5, 2026. After roughly thirty Shopify merchants integrated, OpenAI pivoted to retailer-operated "ChatGPT Apps" (Walmart Sparky, Etsy, Target, Instacart, Expedia, Booking.com). ACP survives as the infrastructure layer, but the consumer-facing shape changed inside OpenAI's surface.

• AP2 became standards-body-governed on April 28, 2026. Google donated the Agent Payments Protocol to the FIDO Alliance alongside the v0.2 release. Sixty organizations contributed. The Verifiable Intent system, co-developed with Mastercard, was also donated. AP2-compatible payment infrastructure will land in PSP roadmaps over the next six to twelve months.

• Visa launched the first protocol-agnostic on-ramp. Intelligent Commerce Connect, released April 8, 2026, accepts agents across Visa TAP, Mastercard MPP, ACP, and UCP simultaneously. The structural move puts one network in the protocol-translator position for the entire category.

• Shared Payment Tokens solve the "person-not-present" problem. When the buyer isn't at the checkout, traditional trust signals break down. SPTs are programmable, scoped, time-limited, and revocable, letting agents initiate payments without ever seeing the buyer's card details.

• The Ninth Circuit answered the legal test on August 4, 2026, and handed the question back to you. In Amazon v. Perplexity the panel vacated the injunction, holding the Assistant "is a tool, not a person for statutory purposes" so "it is the user who 'accesses' Amazon's computers." The CFAA is largely off the table for an agent acting on a logged-in user's instruction. The court's footnote adds that this "does not impair Amazon's ability to regulate access to Amazon.com via private terms of service for its users," so agent access is now governed by your own terms rather than by anti-hacking law. Amazon has petitioned for rehearing en banc, so it is not final.

• The conversion picture reversed in 2026. AI-referred traffic now converts 42% better than non-AI traffic on US retailers, a full reversal from twelve months earlier. AI-driven revenue per visit is 37% higher. The infrastructure is being built for an adoption curve that is already underway, not coming.

This is the final article in a five-part series on the agentic web. Part 1 framed the shift from SEO to AAIO. Part 2 covered how to get cited by AI. Part 3 mapped the protocols. Part 4 explained how agents perceive your website. This article covered where it all leads: transactions.

The thread connecting all five parts is straightforward. Structured data helps AI find you. Clean content helps AI cite you. Accessible HTML helps AI navigate you. Structured commerce protocols help AI buy from you. It's the same principle at every layer: make your business machine-readable, and the machines will do business with you.

Kevin Miller, Stripe's Head of Payments, captured the moment: "Stripe spent the last 15 years optimizing commerce for human shoppers. Now, we're starting to do the same with agents."

The agents are already shopping. The question is whether they can find your store.