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UCP vs. ACP: The Protocol War

A technical comparison between Google's Universal Commerce Protocol (UCP) and OpenAI's Agentic Commerce Protocol (ACP).

The two biggest giants in AI - Google and OpenAI - are fighting a protocol war.

  • Google is backing UCP (Universal Commerce Protocol).
  • OpenAI is backing ACP (Agentic Commerce Protocol).

As a developer or merchant, which one should you choose?

The Philosophy

UCP (Google) is "Resource-Centric". It treats products as resources to be indexed. It's very similar to how Google Search works. It focuses on:

  • Static Files (.well-known/ucp)
  • Read-heavy operations
  • Discoverability

ACP (OpenAI) is "Action-Centric". It treats commerce as a series of functions to be called. It's built around the "Tool Use" paradigm of GPT-4. It focuses on:

  • OpenAPI Specifications (Swagger)
  • Write-heavy operations (Negotiation, Complex Modification)
  • Interaction

The Technical Stack

| Feature | UCP (Google) | ACP (OpenAI) | | :--- | :--- | :--- | | Discovery | /.well-known/ucp | /.well-known/agent-actions | | Data Format | JSON-LD / Extensions | OpenAPI v3.1 | | Auth | OAuth 2.0 (Optional) | OAuth 2.0 (Mandatory) | | State | Stateless (REST) | Stateful (Session-based) |

The Verdict: You Need Both

Here is the hard truth: You cannot pick a winner.

If you bet on UCP, you might lose the ChatGPT users. If you bet on ACP, you might lose the Gemini users.

The UCP-Connect Approach

We believe in a Unified Layer. UCP-Connect is designed to be the "Middleware". You install our plugin, and we generate both protocols.

  • We output the ucp files for Google.
  • We output the OpenAPI specs for OpenAI.

Don't fight the protocol war. Profiteer from it.