OpenAI ACP vs. Google UCP: What’s the Difference

AI is no longer just influencing how shoppers discover products, it’s beginning to act on their behalf.

We’re entering the era of agentic commerce: a world where AI agents don’t just recommend, but search, compare, decide, and transact autonomously. At the center of this shift are two emerging standards:

• OpenAI’s ACP (Agentic Commerce Protocol)

• Google’s UCP (Universal Commerce Protocol)

Both aim to define how AI agents interact with merchants, products, and payments — but they take fundamentally different approaches.

This post breaks down:

• What ACP and UCP actually are

• How they differ (clearly, not theoretically)

• Why merchants shouldn’t view this as a winner-takes-all decision

• And where Nudge fits as the experience layer powering agentic commerce

What Is Agentic Commerce?

Agentic commerce is the evolution of ecommerce from user-driven flows to agent-driven execution.

Instead of:

User searches → clicks → browses → decides → checks out

We’re moving toward:

User expresses intent → AI agent executes end-to-end

That agent might:

• Research options

• Compare prices, reviews, and availability

• Build a cart

• Apply preferences (brand, budget, sustainability, delivery speed)

• Complete checkout — with permission

This requires new protocols that let AI agents safely and reliably discover products. understand offers, interact with carts, and trigger payments.

That’s where ACP and UCP come in.

What Is OpenAI’s ACP?

ACP (Agentic Commerce Protocol) is OpenAI’s framework for enabling AI agents to transact across the open web, not just within a single platform.

It’s designed to let AI assistants like those built on ChatGPT act as delegated shoppers for users.

Core Characteristics of ACP

• Agent-first: Built around AI agents as the primary actor

• Cross-platform: Not tied to a single ecosystem

• Merchant-controlled: Merchants define what agents can do

• Delegated payments: Users authorize agents to transact on their behalf

• API-driven: Commerce happens via structured endpoints, not UI scraping

Conceptually, ACP treats commerce like an API surface — something agents can reason over and execute against.

Why ACP Matters

ACP signals a future where:

• Discovery may happen outside traditional search

• Checkout may happen without a merchant-hosted UI

• Brands must be “agent-readable,” not just human-optimized

This is a foundational shift from page-based commerce to intent-based execution.

What Is Google’s UCP?

UCP (Universal Commerce Protocol) is Google’s answer to agentic commerce but it’s built from a very different starting point.

Rather than creating a net-new agent-first ecosystem, UCP extends Google’s existing commerce infrastructure to support AI-driven interactions.

Core Characteristics of UCP

• Ecosystem-centric: Deeply integrated with Google Search, Shopping, and Gemini

• Structured data-first: Built on Merchant Center feeds and schemas

• Search-native: Optimized for AI-enhanced discovery inside Google surfaces

• Google-mediated checkout: Often routed through Google-controlled flows

• Incremental evolution: Feels like “Search + AI,” not a clean-slate reset

UCP is less about replacing ecommerce flows and more about making Google’s surfaces agent-capable.

Why UCP Matters

UCP ensures that:

• Google remains the dominant gateway for commerce discovery

• AI-driven answers still point into Google-controlled experiences

• Merchants can adopt agentic commerce without abandoning existing SEO and feed strategies

ACP vs. UCP: The Real Differences

Here’s the side-by-side view merchants actually need.

The Short Version

• ACP is betting on a future where agents roam freely across the web

• UCP is betting on a future where agents are deeply embedded inside Google

Neither is “better.” They’re solving different problems.

You Don’t Choose ACP or UCP; You Prepare for Both

This is the most important takeaway for merchants.

ACP and UCP are not mutually exclusive. They represent two demand channels:

1. Agent-native demand

   • Users delegate tasks to AI assistants

   • Commerce happens conversationally

   • ACP-style integrations matter

2. Search-native demand

   • Users still search (even if via AI summaries)

   • Google remains the discovery layer

   • UCP-style readiness matters

The winning brands won’t “pick a protocol.”
They’ll build infrastructure and experiences flexible enough to support both.

What This Means for SEO, Discovery & Conversion

Agentic commerce doesn’t kill SEO, it changes what optimization means.

From Pages → Signals

AI agents don’t care about:

• Beautiful layouts

• Long scroll depth

• Clever UX tricks

They care about:

• Structured product data

• Clear constraints and rules

• Real-time availability

• Price logic

• Eligibility conditions

From Funnels → Decisions

Traditional funnels assume:

impression → click → browse → convert

Agentic commerce assumes:

intent → decision → execution

The optimization surface shifts from pages to decision systems.

Where Nudge Fits: AI Search Visibility + Shoppable Funnels for Agentic Commerce

Here’s the missing layer in most ACP vs. UCP discussions:

Protocols define how agents transact.
But they do not determine which brands agents choose or why.

That decision happens upstream, inside AI search and answer engines.

This is where Nudge fits, as the AI search visibility and shoppable funnel platform for agentic commerce.

1. From SEO to AI Answer Visibility

ACP and UCP change the discovery game:

• AI agents don’t “rank pages”

• They select options

• And often return one or two executable recommendations

Nudge helps brands:

• Structure product, offer, and intent data so it’s legible to AI agents

• Optimize for inclusion inside AI-generated answers, not just SERPs

• Control how products are represented when agents summarize options

Think of Nudge as:

The system that makes your brand “agent-preferred.”

2. Shoppable Funnels Built for AI-Driven Entry Points

Agentic traffic doesn’t land like traditional traffic.

It enters via:

• AI answers

• Assistant recommendations

• “Buy this for me” moments

Nudge turns those entry points into conversion-ready, shoppable funnels by:

• Dynamically generating the right product set, bundle, or offer

• Matching the funnel to intent, not channel

• Ensuring that when an AI agent sends demand, it lands on a path designed to close

This is not static PDP optimization.
It’s intent-aligned funnel composition.

3. Control Without Fighting the Protocols

ACP and UCP are inevitable.
What brands lack is control over outcomes inside them.

Nudge gives brands leverage by:

• Sitting above protocols, not competing with them

• Allowing brands to adapt offers, positioning, and conversion logic without re-integrating ACP or UCP

• Acting as the experimentation layer for AI-driven demand

In practice:

• ACP/UCP decide how commerce happens

• Nudge decides whether it converts

4. Why This Matters Strategically

Without Nudge, brands risk becoming:

• Commoditized inside AI answers

• Interchangeable recommendations

• Price-compared objects instead of differentiated choices

With Nudge, brands:

• Shape how they appear in AI discovery

• Control the funnel agents send users into

• Adapt in real time as agent behavior evolves

That’s the real moat in agentic commerce.