Universal Commerce Protocol (UCP)

The Universal Commerce Protocol (UCP) is an open standard that lets platforms, such as AI agents and apps, discover what a business supports and run commerce flows like checkout with it over REST, MCP or A2A.

Who publishes it. Google announced UCP on 11 January 2026 as an open-source standard developed with retailers and platforms including Shopify, Etsy, Wayfair, Target and Walmart. The specification is Apache-2.0 licensed and credited to the UCP Authors. A five-member Governing Council owns the project’s assets. Google and Shopify, the founding organizations, each hold one permanent seat, and three seats are elected. Google holds the proxy vote for open seats until December 2028 and keeps the ucp.dev domain. Domain Tech Councils, drawn from several companies, set technical direction for areas such as shopping and food ordering. Versions are dates, and the latest release at the time of writing is 2026-08-25.

How it works. A business publishes a profile at /.well-known/ucp. The profile lists the protocol version, the services the business offers with one endpoint per transport, the capabilities it supports, and its payment handlers. Capability names use reverse-domain notation, such as dev.ucp.shopping.checkout, so any domain owner can define an extension without a central registry. A platform sends its own profile URL on each request in the UCP-Agent header, and the business works out which capabilities and versions both sides share. Profiles can publish signing keys as a JWK Set, which lets a business verify a platform’s HTTP Message Signatures without prior onboarding.

One service entry from a business profile, following the specification’s example:

{
  "dev.ucp.shopping": [
    {
      "version": "2026-08-25",
      "spec": "https://ucp.dev/2026-08-25/specification/overview/",
      "transport": "a2a",
      "endpoint": "https://business.example.com/.well-known/agent-card.json"
    }
  ]
}

Relation to A2A and AP2. A business may expose an A2A agent that carries UCP as an A2A extension. UCP’s payment architecture can use AP2 mandates for autonomous purchases.

Neighbouring terms. The Agentic Commerce Protocol, maintained by OpenAI and Stripe, is a separate checkout standard with a similar goal.