UCP
The Universal Commerce Protocol
An open standard for how commerce systems describe themselves to each other, so an agent can find out what you sell and how to buy it without anyone negotiating an integration first.
How discovery works
You publish a JSON profile on your own domain, at a fixed path. Anything that speaks UCP knows where to look, so there is no registry to join and no approval to wait for. The specification calls this permissionless onboarding, and it is the reason a checker like ours can exist: your profile is public by design.
GET https://yourstore.com/.well-known/ucp
The profile declares the version you support, the services and capabilities you offer, such as cart, checkout, fulfilment and catalogue search, and the payment handlers you accept.
Two rules people get wrong
No redirects
The specification states that implementations must not follow redirects on the profile endpoint. If your apex redirects to www and the profile only lives on one of them, discovery can fail for anyone who tries the other. Publish it on both hosts.
Caching is required, not optional
The profile response is meant to carry a Cache-Control header so agents are not forced to hit your origin on every discovery. This is the single most common finding in our checks, and it shows up on profiles served by large platforms as well as hand rolled ones.
Versioning
UCP versions are dates, not numbers. The current version is
2026-04-08.
Because a version string is a date, it tells you when something changed but not whether the change
breaks you, which is why we write up each release rather than just listing tags.
On Shopify?
Then you may already have a UCP profile you did not create. Shopify publishes profiles on merchant storefronts, so the question is usually not whether you have one but whether it is served correctly on the host your customers actually reach.
Find out what yours says