Google launched it with commerce partners including Shopify. It is published openly at ucp.dev.

Where does a UCP profile live?

At /.well-known/ucp on the store's own domain.

How many stores use UCP?

ARC publishes a live count on its Protocol Matrix, split into declared, valid, usable and transacts.

Does having a profile mean agents can buy?

Not always. ARC counts stores that only declare UCP separately from those that return a checkout link.

What is UCP (Universal Commerce Protocol)?

UCP (Universal Commerce Protocol) is an open standard launched by Google with partners including Shopify. A store publishes a profile at /.well-known/ucp that tells AI agents what it supports, like catalog search, cart and checkout. ARC tracks how many stores declare UCP, how many profiles are valid, and how many actually return a checkout.

UCP in one paragraph

UCP is a way for a store to tell an agent what it can do. The public file is /.well-known/ucp. Google launched it with commerce partners, including Shopify. The spec is at ucp.dev.

What a UCP profile is and where it lives

The profile lists capabilities such as catalog search, cart and checkout. ARC fetches it and checks it against the published schema. ARC does not follow a redirect on that path, so a profile that only exists behind a redirect counts as not declared.

Who backs it

Google published it with commerce partners including Shopify. That is the spec's account, not an ARC measurement of who uses it.

How many stores use it

ARC saved checks, accessed 2026-10-13

Declared: 1,896 of 4,318 (43.9%)Measured/.well-known/ucp answered HTTP 200 with a body

Valid: 1,862 of 4,318 (43.1%)MeasuredProfile passed ARC's validation

Usable: 1,717 of 4,318 (39.8%)MeasuredThe UCP catalog tool returned the tested product

Transacts: 1,522 of 4,318 (35.2%)MeasuredUCP create_cart returned a checkout link

Declared isn't the same as working

A store can publish a profile and still fail to return a checkout link. Declared, valid, usable and transacts are four different counts. Not measured is not zero.

How to check your own profile

Use the free UCP validator. It fetches the profile and reports what fails. A valid profile still does not promise a checkout link.

Frequently asked questions

What is UCP (Universal Commerce Protocol)?: UCP (Universal Commerce Protocol) is an open standard launched by Google with partners including Shopify. A store publishes a profile at /.well-known/ucp that tells AI agents what it supports, like catalog search, cart and checkout. ARC tracks how many stores declare UCP, how many profiles are valid, and how many actually return a checkout.
Who made UCP?: Google launched it with commerce partners including Shopify. It is published openly at ucp.dev.
Where does a UCP profile live?: At /.well-known/ucp on the store's own domain.
How many stores use UCP?: ARC publishes a live count on its Protocol Matrix, split into declared, valid, usable and transacts.
Does having a profile mean agents can buy?: Not always. ARC counts stores that only declare UCP separately from those that return a checkout link.

On ARC

Cite this: ARC, arcreport.ai, accessed 2026-10-13, CC-BY-4.0. Protocol figures: ARC saved checks, accessed 2026-10-13 (13 October 2026). Index browser figures: ARC open dataset snapshot 2026-10-12. Platform figures: ARC saved checks, accessed 2026-10-13.

Every figure is labelled Measured, Inferred or Not measured. Not measured is not zero. A missing result is not a mark against a store. ARC stops before payment.