This analysis is part of The AI Shopping Market Map 2026, a deep dive by The Business Engineer.

Three protocols compete to define how AI agents interact with commerce. Here’s a head-to-head comparison across every critical dimension.
Scope
UCP (Google): Full journey—discovery, cart, checkout, support. ACP (OpenAI): Checkout only—focused on transaction completion. Copilot (Microsoft): Checkout + merchant AI assistants (Brand Agents).
Architecture
UCP: Open-source, any transport (REST/MCP/A2A), decentralized. ACP: Stripe infrastructure, delegated payment tokens, centralized via OpenAI. Copilot: Shopify integration, Brand Agent SDK, hybrid approach.
Monetization
UCP: Ads (Direct Offers at intent). ACP: Fees (transaction fee per purchase). Copilot: SaaS (enterprise subscriptions).
Key Strength
UCP: Billions of intent queries + open standard adoption = network effects. ACP: 810 million daily active users + conversational commerce dominance. Copilot: Enterprise relationships + B2B AI commerce.
The Real Question
It’s not about which protocol is “better”—it’s about distribution. UCP owns intent (search queries). ACP owns conversation (chat users). Copilot owns enterprise (B2B relationships). Merchants will support multiple protocols—just as they support multiple payment methods today.









