Agentic Commerce Protocols: UCP, ACP, AP2 and A2A
Four protocols now shape how AI agents shop and pay: UCP, ACP, AP2 and A2A. See what each does for a retailer and which explainer to read first.
Agentic commerce protocols are shared rules that let AI agents find products, check out and pay with a shopper’s permission. Each protocol handles a different part of that process, from reading a catalogue to recording payment approval.
Explore this topic
- Universal Commerce Protocol Explained for Retailers 2026Google UCP is an open standard that lets AI agents find products and check out on your store, and it may change what you need to do this year.
- Agentic Commerce Protocol Explained for Retailers 2026How does an agentic commerce protocol work? ACP lets ChatGPT and other agents send orders to your store. See the flow and what merchants must build.
- Agent Payments Protocol Explained for Retailers 2026The AP2 protocol lets an AI agent prove a shopper approved a payment, which is why card networks and gateways care about how its mandates work.
- A2A Protocol Explained for Retailers 2026Google’s A2A lets AI agents talk to each other. Compare A2A vs MCP and find out which one matters when a shopping agent reaches your store.
Which Protocol Does What
Universal Commerce Protocol (UCP), co-developed by Google, Shopify and other retailers, covers catalogue access and checkout, with support for orders after purchase. Read the UCP explainer when your platform announces a connection to Google’s shopping experiences.
OpenAI and Stripe developed Agentic Commerce Protocol (ACP) for commerce between agents and retailers. Its checkout specification sets how an agent builds and completes a purchase. OpenAI’s merchant documentation also describes structured product feeds for discovery. The ACP explainer separates those feed and checkout requirements.
Agent Payments Protocol (AP2) records the shopper’s authority to spend through signed purchase and payment instructions. Google developed AP2 and donated it to the FIDO Alliance. Read the AP2 explainer to understand what an agent can buy under the shopper’s permission.
Agent2Agent (A2A) lets separate agents exchange information and coordinate tasks. Google created A2A, which is now a Linux Foundation project. The A2A explainer explains agent communication and how commerce systems can use it alongside payment protocols.
Which Protocols Need Work From Your Store
Your platform or payment provider can handle protocol support as part of its commerce services. The work for your store depends on the shopping channel you want to reach and the connection your provider supplies. A custom UCP or ACP checkout connection needs development work. AP2 payment support depends on the participating payment services, while A2A connects the agents used by those systems.
For ChatGPT product discovery, OpenAI’s ACP documentation describes a product feed or catalogue integration. Keep product details complete, with accurate variants and availability. Checkout support is a separate connection, and implementing ACP does not automatically admit your store to every AI shopping platform.
Follow your platform’s announcements to learn which connections it supplies and which settings your store must complete. For the wider shift, read how agentic commerce works. Use the store preparation checklist when you’re ready to work through catalogue and checkout readiness.