# Universal Commerce Protocol (UCP)

Category: [Agents & Protocols](https://seo-geo-glossary.com/en/glossary/category/agents-protocols/) › [Agentic commerce](https://seo-geo-glossary.com/en/glossary/category/agents-protocols/agentic-commerce/) · Also known as: UCP

The **Universal Commerce Protocol (UCP)** is an open standard that lets AI agents discover products and complete purchases at businesses. Google introduced it in January 2026 and describes it as enabling checkout in Google Search AI Mode and Gemini. The specification is open source and hosted on GitHub; Shopify says it co-developed the standard with Google.

## How does UCP work?

UCP models commerce as **capabilities**, which are building blocks such as checkout, catalog, cart and order management. **Extensions** add domain-specific features on top, for example discounts or fulfillment. Businesses and agents publish profiles that declare what they support, and the two sides use the overlap. Shopify compares this negotiation to HTTP content negotiation.

According to the Google Developers Blog, a merchant publishes its profile at `/.well-known/ucp`, so an agent can read the supported services and endpoints without a hard-coded integration. UCP can be used over REST, over the Model Context Protocol (MCP) and over the Agent2Agent protocol (A2A). Payments are handled separately from checkout, and UCP works with the Agent Payments Protocol (AP2). Merchants remain the merchant of record, according to Google. Native checkout in the AI surface is the default path. According to Google, embedded checkout is an optional path for specific, approved merchants. Post-purchase support such as tracking and returns is listed on Google's roadmap as an upcoming feature (as of October 2026). The specification is licensed under Apache 2.0 on GitHub.

## Example

A retailer publishes a profile at `https://shop.example/.well-known/ucp` that lists checkout and discounts as capabilities. A user asks Gemini for a rain jacket. The agent reads the profile, finds the checkout capability and starts the purchase through the endpoint named there.

## UCP and ACP

The Agentic Commerce Protocol (ACP) from Stripe and OpenAI addresses a similar goal. UCP is built around Google surfaces, and ACP was built around ChatGPT.

## Common mistakes

- **Serving the profile without HTTPS.** According to the specification, profiles must be served over HTTPS.
- **Placing the profile behind a redirect.** Profile endpoints must not use redirects (3xx).
- **Leaving out required sections.** `ucp.version`, `ucp.services` and `ucp.payment_handlers` are required, even if the registries are empty.

## FAQ

**Who is behind UCP?**
Google and partners. The project is open source on GitHub, and ucp.dev describes it as built collaboratively with industry.

**Does UCP replace product feeds?**
Google states that UCP builds on existing Google Merchant Center shopping feeds for product discovery.

## At a glance

- **Publisher:** Google with commerce partners (incl. Shopify, Etsy, Wayfair, Target, Walmart)
- **Connects:** platforms and AI agents with businesses; profile at /.well-known/ucp
- **Status:** stable, version 2026-08-25
- **License:** Apache 2.0
- **Specification:** [UCP: Specification overview](https://ucp.dev/latest/specification/overview/)

Last checked: October 8, 2026

## AI agent protocols compared

| Protocol | Publisher | Connects | Status and version |
|---|---|---|---|
| MCP (Model Context Protocol) | by Anthropic, since 2025-12-09 at the Agentic AI Foundation (Linux Foundation) | AI applications with servers that provide data, tools and prompts | current version 2026-07-28 |
| A2A (Agent2Agent) | by Google, donated to the Linux Foundation; joining the Agentic AI Foundation announced on 2026-08-27 | AI agents from different vendors with each other | specification 1.0 (release v1.0.1 of 2026-05-28) |
| ACP (Agentic Commerce Protocol) | OpenAI and Stripe | buyers and their AI agents with businesses and payment providers | beta, current version 2026-04-17 |
| AP2 (Agent Payments Protocol) | Google; standardisation continues in FIDO Alliance working groups | AI agents, merchants and payment providers for payments on behalf of users | v0.2 (release of 2026-04-28) |
| UCP (Universal Commerce Protocol) | Google with commerce partners (incl. Shopify, Etsy, Wayfair, Target, Walmart) | platforms and AI agents with businesses (profile at /.well-known/ucp) | stable, version 2026-08-25 |
| WebMCP | W3C Web Machine Learning Community Group (editors from Microsoft and Google) | websites with AI agents in the browser | draft (Draft Community Group Report of 2026-10-02), not a W3C standard; origin trial in Chrome from version 149 |
| NLWeb | Microsoft (announced 2025-05-19), open source under the MIT licence | websites (Schema.org and RSS content) with users and AI agents; every instance is an MCP server | open-source project without a published version number |

Sources: [Model Context Protocol: Specification 2026-07-28](https://modelcontextprotocol.io/specification/2026-07-28); [Model Context Protocol: Versioning](https://modelcontextprotocol.io/specification/versioning); [Anthropic: Donating the Model Context Protocol and establishing the Agentic AI Foundation (2025-12-09)](https://www.anthropic.com/news/donating-the-model-context-protocol-and-establishing-of-the-agentic-ai-foundation); [A2A Protocol: Specification](https://a2a-protocol.org/latest/specification/); [A2A: A new chapter for A2A, joining the Agentic AI Foundation (2026-08-27)](https://a2a-protocol.org/latest/blog/2026/08/27/a-new-chapter-for-a2a-joining-the-agentic-ai-foundation/); [A2A releases (GitHub)](https://github.com/a2aproject/A2A/releases); [Agentic Commerce Protocol (GitHub)](https://github.com/agentic-commerce-protocol/agentic-commerce-protocol); [AP2: Agent Payments Protocol](https://ap2-protocol.org/); [AP2 releases (GitHub)](https://github.com/google-agentic-commerce/AP2/releases); [Universal Commerce Protocol: Specification overview (2026-08-25)](https://ucp.dev/latest/specification/overview/); [Universal Commerce Protocol](https://ucp.dev/); [WebMCP: Draft Community Group Report (W3C Web Machine Learning CG)](https://webmachinelearning.github.io/webmcp/); [Chrome for Developers: WebMCP (updated 2026-10-07)](https://developer.chrome.com/docs/ai/webmcp); [Microsoft: Introducing NLWeb (2025-05-19)](https://news.microsoft.com/source/features/company-news/introducing-nlweb-bringing-conversational-interfaces-directly-to-the-web/); [NLWeb (GitHub)](https://github.com/nlweb-ai/NLWeb). Last checked: October 8, 2026

*Diagram: Which protocol covers what?.* Map of agent protocols as of 2026-10-08: which connection each protocol covers, who publishes it and what its status is. In commerce, ACP, UCP and AP2 overlap, and several protocols build on MCP or A2A. Versions change quickly.

## Related terms

- [Agentic commerce](https://seo-geo-glossary.com/en/glossary/agentic-commerce/index.md)
- [Agentic Commerce Protocol (ACP)](https://seo-geo-glossary.com/en/glossary/agentic-commerce-protocol/index.md)
- [Agent Payments Protocol (AP2)](https://seo-geo-glossary.com/en/glossary/agent-payments-protocol/index.md)
- [MCP (Model Context Protocol)](https://seo-geo-glossary.com/en/glossary/mcp/index.md)
- [Agent2Agent protocol (A2A)](https://seo-geo-glossary.com/en/glossary/agent2agent-protocol/index.md)
- [Google Merchant Center](https://seo-geo-glossary.com/en/glossary/google-merchant-center/index.md)

## Sources

- [Universal Commerce Protocol (UCP) – Google Merchant Center Developers](https://developers.google.com/merchant/ucp)
- [Universal Commerce Protocol – ucp.dev](http://ucp.dev/)
- [Under the Hood: Universal Commerce Protocol (UCP) – Google Developers Blog (Jan 11, 2026)](https://developers.googleblog.com/under-the-hood-universal-commerce-protocol-ucp/)
- [Shopify Engineering: UCP](https://shopify.engineering/UCP)
- [universal-commerce-protocol/ucp – GitHub](https://github.com/universal-commerce-protocol/ucp)
- [Universal Commerce Protocol: Specification overview (2026-08-25)](https://ucp.dev/latest/specification/overview/)

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Last updated: October 8, 2026
URL: https://seo-geo-glossary.com/en/glossary/universal-commerce-protocol/