Whether a store publishes a Universal Commerce Protocol manifest depends mostly on the platform it runs on. Google announced the protocol in January 2026 as a standard developed with Shopify, Etsy, Wayfair, Target and Walmart for buying through AI assistants. Stores that support it serve a small file at /.well-known/ucp that tells an AI agent which UCP functions they offer, such as checkout, so the agent can buy from them through the protocol. On November 7, 2026, TechnologyChecker, which sells data on the technology websites use, probed 19,044 storefronts on nine ecommerce platforms for that file. It found one on 85.7% of BigCommerce stores, 73.0% of Shopify stores and 65.0% of Wix stores. On the other six platforms the share was 4.6% or lower.
The shares count stores whose response the probe could read, leaving out errors, blocks and timeouts. Shopify says Shopify Catalog and UCP are enabled by default for its merchants, which matches its high share. Shopify stores among Cloudflare Radar's 100,000 most popular domains published the file less often, at 65.2%, against 83.9% for Shopify stores ranked from 100,000 to 1,000,000.
Across the wider web the file is still rare. Cloudflare Radar's scan of 115,468 popular domains on November 2, 2026 found a UCP manifest on 4.7% of them and on 22.1% of the domains it classifies as ecommerce, according to TechnologyChecker's analysis of the Radar data.
The shares on the other platforms describe where they stood on November 7. Salesforce released UCP checkout in Gemini and AI Mode for its B2C Commerce stores on October 26, 2026, and Google approves each store from a waitlist before checkout appears, so that platform's share can rise as stores are admitted.
You can check your own store in a minute. Open your domain followed by /.well-known/ucp in a browser, and a store that publishes a manifest shows a block of JSON at that address. On BigCommerce, Shopify or Wix, where most stores have the file, a store without it is worth raising with your developer or the platform's support. On the other platforms, publishing it is a project for your developers or your platform's UCP integration.
Common questions
What is a UCP manifest?
A file a store serves at /.well-known/ucp that tells AI agents which Universal Commerce Protocol functions it supports, such as checkout. An agent that uses the protocol reads it before buying from the store.
Which ecommerce platforms publish one for most stores?
In a November 7, 2026 probe of 19,044 storefronts, 85.7% of BigCommerce stores, 73.0% of Shopify stores and 65.0% of Wix stores published a UCP manifest. On Shopware, Magento, Squarespace, Salesforce Commerce Cloud, WooCommerce and PrestaShop the share was between 1.7% and 4.6%.
How common is the file across the web?
Cloudflare Radar found a UCP manifest on 4.7% of 115,468 popular domains on November 2, 2026, and on 22.1% of the domains it classifies as ecommerce.
How do I check whether my store publishes one?
Open your domain followed by /.well-known/ucp in a browser. A store that publishes a manifest returns a block of JSON at that address.