Agentic commerce protocols
Agentic Commerce Protocol (ACP)
Introduced in September of last year by OpenAI and fintech company Stripe, ACP launched in tandem with ChatGPT’s Instant Checkout feature, letting autonomous agents assist users in completing purchases within the chatbot’s interface. The open standard provides the connective tissue between AI, merchant, and payment systems, enabling payment detail verification, order confirmation, and purchase approval.
In March of this year, OpenAI announced that Instant Checkout purchases would migrate to third-party applications. Now, users can discover products inside the ChatGPT experience, but OpenAI will no longer own the entire transaction; purchases will be handled on the retailer’s own site or app. ACP still links ChatGPT to merchants.
Universal Commerce Protocol (UCP)
Debuted in January, UCP is designed to support agentic commerce across the shopping journey from product discovery and price negotiations to checkout and post-purchase support. It sets out a universal system for agents and tech to work together across consumer interfaces, business platforms, and payment tech. Created by Google in conjunction with a commerce partners iShopify, Etsy, Wayfair, Target, and Walmart, UCP is compatible with a variety of other agentic protocols, including MCP, A2A, and AP2.
Amazon, Meta, Microsoft, Salesforce, and Stripe all joined the UCP Tech Council in April 2026. Today, UCP is by and far the most dominant commerce protocol.
Agent Payments Protocol (AP2)
Created by Google in collaboration with Coinbase, PayPal, Mastercard, American Express, and others, AP2 lets AI agents securely exchange information and conduct commerce activity on users’ behalfs. It is built to keep real people in control, with mechanisms for verifying both the fact that a given user authorized a specific purchase (confirmed with a series of cryptographically signed mandates), and that the payment information provided is valid (confirmed with the help of the infrastructure partner that actually transfers funds). AP2 provides the answer to both of these factors in a format that any network or merchant can easily verify. AP2 is positioned as a payments layer add-on to A2A and MCP.
x404
Established by Coinbase and Cloudflare and folded under management of the Linux Foundation in April of this year, x402 is a reimagined, crypto- and AI-friendly version of the HTTP 402 “Payment Required” status code. The standard lets AI agents make payments using stablecoins. Rather than requiring a user or agent to sign up for an account, input their payment information, or manage an API, an agent or or human user can pay for a product or resource directly inside a standard HTTP request workflow using stablecoins, primarily USDC. It is blockchain-agnostic.
Founding members of the protocol include Google, Mastercard, AWS, American Express, Microsoft, Stripe, Circle, and Fiserv. Google integrated x402 into AP2 to act as the default stablecoin transaction rail last September.
Trusted Agent Protocol (TAP)
TAP, released in October 2025 by Visa in partnership with Cloudflare, creates a secure connection between agents and merchants throughout each step in an agentic commerce transaction. It is also meant to help merchants distinguish between trustworthy agents working on users’ behalfs and malicious or fraudulent bots. With TAP, an agent signs up and gets a cryptographic key tied to its unique identity; then, for each request that an agent sends using that key, the given merchant or infrastructure provider can check a reliable registry to pinpoint which agent sent the request, ensure its validity, and make sure that agent has been authorized to take actions. If all these criteria are met, the merchant can allow the agent to browse or check out. TAP relies primarily on traditional web cryptography, the most central being HTTP message signatures. Early adopters of include Coinbase, Microsoft, Shopify, Stripe and Worldpay.
