UCP is an open source standard, announced by Google in January 2026 and co-developed with Shopify, Etsy, Wayfair, Target, and Walmart. A business supports it by publishing a JSON manifest at /.well-known/ucp describing its services, capabilities, payment handlers, and signing keys, in a structure AI agents can query directly.
Who built UCP, and when
Sundar Pichai, CEO of Google and Alphabet, announced UCP at the NRF 2026 keynote on January 11, 2026, framing the case for a shared standard rather than one-off integrations between every merchant and every AI agent.
“…the industry needs a protocol that works at global scale…”
Sundar Pichai, at the NRF 2026 keynote where UCP was announcedUCP was co-developed with Shopify, Etsy, Wayfair, Target, and Walmart, and is endorsed by more than 20 additional companies, including Visa, Mastercard, Stripe, and The Home Depot, according to Google's own developer blog.
What a UCP manifest actually contains
A UCP manifest is a JSON document published at the well known path /.well-known/ucp on a business's domain. The current specification defines a small set of required and recommended fields:
ucp.services, an object keyed by service name, where each entry is an array of descriptors declaring a version and a transport (rest, mcp, a2a, or embedded).
ucp.payment_handlers, an object keyed by handler namespace, listing which payment methods the store accepts.
A root level signing_keys array. An empty array is valid for a store that is not yet signing payloads, but the key itself must be present.
ucp.capabilities, describing which shopping intents the store can handle, such as checkout or cart operations.
These are the exact fields our UCP checker validates against, whether you are checking a live site or you want to paste and validate a manifest before you deploy it.
UCP vs ACP: the two major standards
UCP is not the only open standard in this space. The Agentic Commerce Protocol (ACP), co-developed by Stripe and OpenAI, launched earlier, in September 2025, and powers agent checkout inside ChatGPT.
| UCP | ACP | |
|---|---|---|
| Announced | January 11, 2026 | September 29, 2025 |
| Led by | Google, Shopify, Etsy, Wayfair, Target, Walmart | Stripe, OpenAI, later joined by Meta |
| Manifest location | /.well-known/ucp | Defined via ACP's own commerce feed specification |
| Primary surface | Google AI Mode and other UCP-compatible agents | ChatGPT and other ACP-compatible agents |
The two are independently governed and not interchangeable, but a merchant can implement either, or both, depending on which agents its customers actually use. For a broader look at the category both standards serve, see our guide to what agentic commerce actually is.
Why UCP matters for merchants
McKinsey research estimates AI agents could mediate $3 trillion to $5 trillion of global consumer commerce by 2030. An agent cannot reliably transact with a store it cannot parse, so whether a merchant's manifest is present, complete, and correctly structured is a real factor in whether UCP-compatible agents can complete a purchase there at all, not just a compliance checkbox.
Check if a site supports UCP
Enter a domain to see whether it publishes a valid UCP manifest, with a category breakdown and a specific fix for every issue.
Frequently asked questions
UCP is an open source standard Google developed together with Shopify, Etsy, Wayfair, Target, and Walmart, and it is endorsed by more than 20 additional companies. It is open for any business or platform to implement, not a proprietary Google product.
At the well known path /.well-known/ucp on the business's domain, served as a JSON document.
UCP was announced by Google in January 2026 and co-developed with Shopify, Etsy, Wayfair, Target, and Walmart. ACP launched earlier, in September 2025, co-developed by Stripe and OpenAI, and powers agent checkout inside ChatGPT. They are separate, independently governed standards, and a merchant can support either or both.
Request https://the-domain/.well-known/ucp directly, or use a checker tool that does this for you and reports what is present, missing, or misconfigured against the current specification.